[Agda] Univalent foundations in Agda lecture notes

[Martin Escardo]

I would like to advertise these lecture notes on univalent foundations 
of mathematics with Agda:

  https://www.cs.bham.ac.uk/~mhe/HoTT-UF-in-Agda-Lecture-Notes/index.html

Issues and pull requests via github are welcome.

(This relies on the pre-released version 2.6.0 of Agda, mainly for 
`variables` and for the new options for generating html from Agda 
literate code. I thank the dedicated development team.)

Martin