docs(project): Add docstrings to functions in project

[MarieSacksick]

Add docstrings to the functions in the project class.

[tuscland]

Minor adjustments for more idiomatic english, simplifications, and one fix (view instead of item).

[augustebaum]

Thanks for the added precision, this is really welcome. I made a few changes but I realize that not everything was previously agreed upon and we can discuss it. A few notable remarks:

• The Attributes is for documenting classes, not functions. When a function returns an object of type A, it makes sense to just say it returns an A and document in a specific place what an A is, in depth
• Each section of the docstring needs to be separated from the others by a blank line (that's for the docs generator to understand that a new paragraph is starting)
• The Returns block already explains what is returned, so writing "Returns ..." in the description is redundant (see numpydoc spec)
• The Raises block already says which exceptions can be raised, so writing "Raises a KeyError" in the description is redundant (see numpydoc spec)

[augustebaum]

Nice work!