Improve the documentation of the project

[Miguel-Romero-Mateos]

A few problems I found:

• There's documentation everywhere: in the project's folders, in the Readme file and in a few webs and a PDF file I found.
• The documentation is in some cases severely outdated, for example this page.
• None of the documentation is explicitly dated.

This makes all documentation untrustworthy, as you never know if the new documentation you found dates back of 2023, which would be somewhat acceptable, or 2015.