Add official Quake 2 repos

[kparal]

Quake 2 official repos are currently not listed.

The official repo for the original game is here:
https://github.com/id-Software/Quake-2

And the official repo for the 2023 re-release (the "remastered" version, although not called that officially) is here:
https://github.com/id-Software/quake2-rerelease-dll