Add new Section for Showcasing Third Party Libraries and Extensions

[dellis1972]

Link to Document

No response

Description

We currently have a Showcase for games, it would be nice to have a separate section for third party extensions like MonoGame.Extended or JitterPhysics2 etc.

[Apostolique]

I've been maintaining a list here: https://github.com/Apostolique/MonoGameLibraries.