[DOC] General PR to improve docs (#1705)

### Description

This PR aims to improve current docstring and revamp the
contribute/installation page for users looking to get working copies of
`pytorch-forecasting` or would like to get a developmental version for
contributing.

### Checklist

- [x] Linked issues (if existing)
#1635 and #1698 
- [ ] Amended changelog for large changes (and added myself there as
contributor)
- [ ] Added/modified tests
- [ ] Used pre-commit hooks when committing to ensure that code is
compliant with hooks. Install hooks with `pre-commit install`.
To run hooks independent of commit, execute `pre-commit run --all-files`

docs/source/getting-started.rst

@@ -9,23 +9,32 @@ Installation
 
 .. _install:
 
-If you are working windows, you need to first install PyTorch with
+If you are working Windows, you need to first install PyTorch with
 
-``pip install torch -f https://download.pytorch.org/whl/torch_stable.html``.
+.. code-block:: bash
+
+    pip install torch -f https://download.pytorch.org/whl/torch_stable.html
 
 Otherwise, you can proceed with
 
-``pip install pytorch-forecasting``
+.. code-block:: bash
+
+    pip install pytorch-forecasting
+
 
+Alternatively, to install the package via ``conda``:
 
-Alternatively, to installl the package via conda:
+.. code-block:: bash
 
-``conda install pytorch-forecasting pytorch>=1.7 -c pytorch -c conda-forge``
+    conda install pytorch-forecasting pytorch>=1.7 -c pytorch -c conda-forge
 
 PyTorch Forecasting is now installed from the conda-forge channel while PyTorch is install from the pytorch channel.
 
 To use the MQF2 loss (multivariate quantile loss), also install
-`pip install pytorch-forecasting[mqf2]`
+
+.. code-block:: bash
+
+    pip install pytorch-forecasting[mqf2]
 
 
 Usage

docs/source/index.rst

@@ -66,7 +66,7 @@ The :ref:`Tutorials <tutorials>` section provides guidance on how to use models
    models
    metrics
    faq
-   contribute
+   installation
    api
    CHANGELOG
 

docs/source/installation.rst

@@ -0,0 +1,199 @@
+Installation
+============
+
+``pytorch-forecasting`` currently supports:
+
+* Python versions 3.8, 3.9, 3.10, 3.11, and 3.12.
+* Operating systems : Linux, macOS, and Windows
+
+Installing pytorch-forecasting
+------------------------------
+
+``pytorch-forecasting`` is a library built on top of the popular deep learning framework ``pytorch`` and
+heavily uses the Pytorch Lightning library ``lightning`` for ease of training and multiple GPU usage.
+
+You'll need to install ``pytorch`` along or before with ``pytorch-forecasting`` in order to get a working
+install of this library.
+
+If you are working Windows, you can install PyTorch with
+
+.. code-block:: bash
+
+    pip install torch -f https://download.pytorch.org/whl/torch_stable.html
+
+.. note::
+  It is recommended to visit the Pytorch official page https://pytorch.org/get-started/locally/#start-locally to
+  figure out which version of ``pytorch`` best suits your machine if you are
+  unfamiliar with the library.
+
+Otherwise, you can proceed with:
+
+.. code-block:: bash
+
+    pip install pytorch-forecasting --extra-index-url https://download.pytorch.org/whl/cpu
+
+
+Alternatively, to install the package via ``conda``:
+
+.. code-block:: bash
+
+    conda install pytorch-forecasting pytorch>=2.0.0 -c pytorch -c conda-forge
+
+PyTorch Forecasting is now installed from the conda-forge channel while PyTorch is install from the pytorch channel.
+
+To install ``pytorch-forecasting`` with the use of the MQF2 loss (multivariate quantile loss), run:
+
+.. code-block:: bash
+
+    pip install pytorch-forecasting[mqf2]
+
+
+To install the Pytorch Lightning library, please visit their `official page <https://lightning.ai/docs/pytorch/stable/starter/installation.html>`__ or run:
+
+.. code-block:: bash
+
+    pip install lightning
+
+
+Obtaining a latest ``pytorch-forecasting`` version
+--------------------------------------------------
+
+This type of installation obtains a latest static snapshot of the repository, with
+various features that are not published in a release. It is mainly intended for developers
+that wish to build or test code using a version of the repository that contains
+all of the latest or current updates.
+
+.. code-block:: bash
+
+    pip install git+https://github.com/sktime/pytorch-forecasting.git
+
+
+To install from a specific branch, use the following command:
+
+.. code-block:: bash
+
+    pip install git+https://github.com/sktime/pytorch-forecasting.git@<branch_name>
+
+
+Contributing to ``pytorch-forecasting``
+---------------------------------------
+
+Contributions to PyTorch Forecasting are very welcome! You do not have to be an expert in deep learning
+to contribute. If you find a bug - fix it! If you miss a feature - propose it!
+
+To obtain an editible version ``pytorch-forecasting`` for development or contributions,
+you will need to set up:
+
+* a local clone of the ``pytorch-forecasting`` repository.
+* a virtual environment with an editable install of ``pytorch-forecasting`` and the developer dependencies.
+
+The following steps guide you through the process:
+
+Creating a fork and cloning the repository
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+1.  Fork the `project
+    repository <https://github.com/sktime/pytorch-forecasting>`__ by
+    clicking on the 'Fork' button near the top right of the page. This
+    creates a copy of the code under your GitHub user account. For more
+    details on how to fork a repository see `this
+    guide <https://help.github.com/articles/fork-a-repo/>`__.
+
+2.  `Clone <https://docs.github.com/en/github/creating-cloning-and-archiving-repositories/cloning-a-repository>`__
+    your fork of the pytorch-forecasting repo from your GitHub account to your local
+    disk:
+
+    .. code:: bash
+
+      git clone [email protected]:<username>/sktime/pytorch-forecasting.git
+      cd pytorch-forecasting
+
+    where :code:`<username>` is your GitHub username.
+
+3.  Configure and link the remote for your fork to the upstream
+    repository:
+
+    .. code:: bash
+
+      git remote -v
+      git remote add upstream https://github.com/sktime/pytorch-forecasting.git
+
+4.  Verify the new upstream repository you've specified for your fork:
+
+    .. code:: bash
+
+      git remote -v
+      > origin    https://github.com/<username>/sktime/pytorch-forecasting.git (fetch)
+      > origin    https://github.com/<username>/sktime/pytorch-forecasting.git (push)
+      > upstream  https://github.com/sktime/pytorch-forecasting.git (fetch)
+      > upstream  https://github.com/sktime/pytorch-forecasting.git (push)
+
+Setting up an editible virtual environment
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+1. Set up a new virtual environment. Our instructions will go through the commands to set up a ``conda`` environment which is recommended for ``pytorch-forecasting`` development.
+The process will be similar for ``venv`` or other virtual environment managers.
+
+  .. warning::
+       Using ``conda`` via one of the commercial distributions such as Anaconda
+       is in general not free for commercial use and may incur significant costs or liabilities.
+       Consider using free distributions and channels for package management,
+       and be aware of applicable terms and conditions.
+
+In the ``conda`` terminal:
+
+2. Navigate to your local pytorch-forecasting folder, :code:`cd pytorch-forecasting` or similar
+
+3. Create a new environment with a supported python version: :code:`conda create -n pytorch-forecasting-dev python=3.11` (or :code:`python=3.12` etc)
+
+   .. warning::
+       If you already have an environment called ``pytorch-forecasting-dev`` from a previous attempt you will first need to remove this.
+
+4. Activate the environment: :code:`conda activate pytorch-forecasting-dev`
+
+5. Build an editable version of pytorch-forecasting.
+In order to install only the dev dependencies, :code:`pip install -e ".[dev]"`
+If you also want to install soft dependencies, install them individually, after the above,
+or instead use: :code:`pip install -e ".[all_extras,dev]"` to install all of them.
+
+Contribution Guidelines and Recommendations
+-------------------------------------------
+
+Submitting pull request best practices
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To ensure that maintainers and other developers are able to help your issues or
+review your contributions/pull requests, please read the following guidelines below.
+
+* Open issues to discuss your proposed changes before starting pull requests.
+  This ensures that other developers or maintainers have adequete context/knowledge
+  about your future contribution so that it can be swiftly integrated into the code base.
+
+* Adding context tags to the PR title.
+  This will greatly help categorize different types of pull requests without having
+  to look at the full title. Usually tags that start with either [ENH] - Enhancement:
+  adding a feature, or improving code, [BUG] - Bugfixes, [MNT] - CI: test framework, [DOC] -
+  Documentation: writing or improving documentation or docstrings.
+
+* Adding references to other links or pull requests.
+  This helps to add context about previous or current issues/prs that relate to
+  your contribution. This is done usually by including a full link or a hash tag '#1234'.
+
+Technical Design Principles
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+When writing code for your new feature, it is recommended to follow these
+technical design principles to ensure compatability between the feature and the library.
+
+* Backward compatible API if possible to prevent breaking code.
+* Powerful abstractions to enable quick experimentation. At the same time, the abstractions should
+  allow the user to still take full control.
+* Intuitive default values that do not need changing in most cases.
+* Focus on forecasting time-related data - specificially timeseries regression and classificiation.
+  Contributions not directly related to this topic might not be merged. We want to keep the library as
+  crisp as possible.
+* Install ``pre-commit`` and have it run on every commit that you make on your feature branches.
+  This library requires strict coding and development best practices to ensure the highest code quality.
+  Contributions or pull requests that do not adhere to these standards will not likely be merged until fixed.
+  For more information on ``pre-commit`` you can visit `this page <https://www.sktime.net/en/stable/developer_guide/coding_standards.html#using-pre-commit>`__
+* Always add tests and documentation to new features.