[Agda] Comprehensive Archive of Agda Theories and other collaboration facilities

[Vag Vagoff]

It is useful to have a collaboration mechanism together with 
Comprehensive Archive of Agda Theories that includes:

- Enumeration of all Agda theories
- Comprehensive map of Agda (1 and 2) materials
- Materials to teach novices
- Advertising board to announce plans to share parts of future theories 
to reduce development efforts
- ...

It is worth to add a issue ticket for it?