SNEWS CS Documentation Improvements

[KaraMelih]

This PR fixes the readthedocs build, restructures some of the documentation files, and removes the setuptools installation to avoid possible confusion.

This version solely depends on the poetry installation.

The documentation still needs to be improved before making the PR

[KaraMelih]

after discussing with @justinvasel I decided to bring back the setuptools installation. (so the branch name no longer makes sense, sorry.)

This PR introduces the following;

• Clean some of the files
• rename doc -> docs
• add 2 more packages to poetry dependencies: sqlalchemy and tabulate
• create requirements file from the poetry dependencies
• separate, isolated requirements for the readthedocs under docs folder
• improved documentation
• added a developers page in the documentation