Add documentation to the project

[wurmc]

User Story

As a:

developper

I want:

more documentation inside the code or aside from it.

so that:

complications can be explained or understanding is possible faster for future developpers.

Acceptance criteria:

• [ ]

Additional info:

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Please tag this issue if you are sure to which tag(s) it belongs.

[Gargamil]

Maybe some service / framework like 'read the docs' https://readthedocs.org is useful