Add missing documentation

[SuperGamingBros4]

The docs at https://evilfactory.github.io/LuaCsForBarotrauma are missing documentation for different types (e.g. ChatMessage).

The ChatMessage object should be present and documented rather than only being present in one of the example mod files (at least as far as I can tell). Please add documentation for this instead of leaving it as a small example from 2 years ago.

[SomeRandomNoobKekeke]

[SuperGamingBros4]

Upon further inspection, these are classes defined within the Barotrauma source code. There honestly should be a note or something in the documentation to point you toward Barotrauma's source code. Put it under Common Questions and Getting Started as to help people when they get started, obviously, and help people if they, like me, get stuck trying to figure it out for a few hours.

[MapleWheels]

We're reworking the codebase. Any documentation updates outside of small fixes would just be wasted time since we'd have to throw it out anyways.