Updated documentation with installation guide (#404)

docs/content/installation.md

@@ -0,0 +1,28 @@
+# Installation
+
+To install `minigrid`, the easiest way is to use `pip`:
+
+```bash
+pip install minigrid
+```
+
+However, if you would like to build on top of `minigrid`, you would need to install it from source. To do this, first clone the repository:
+
+```bash
+git clone https://github.com/Farama-Foundation/Minigrid.git
+```
+
+Then, install the package:
+
+```bash
+cd Minigrid
+python3 -m pip install .
+```
+
+If you want to install the package in [development mode](https://setuptools.pypa.io/en/latest/userguide/development_mode.html), use the following command instead:
+
+```bash
+python3 -m pip install -e .
+```
+
+An installation in development mode (i.e., an editable install) is useful if you want to modify the source code of `minigrid` and have your changes take effect immediately.