[DOC] Add documentation to Menus!

[japtar10101]

Is your request related to a feature? Please describe.

Menus.

Describe what changes in documentation you'd like.

This project is lacking in documentation!

Tasklist

• Research and evaluate what needs to be documented.

Additional context

Carry-over from the old Bitbucket Mercurial project:
https://bitbucket.org/OmiyaGames/hg-template-unity-project/issues/21/add-documentation-to-menus