mark errata
cite 2.11.3 and 2.11.5 in 6.2.8, close #527
unmarked errata for 72b677d
Add a label to definition of quasi inverse
Merge pull request #538 from marcbezem/master

Add a label to definition of quasi inverse, needed for HoTTBook.v in the HoTT library
Merge pull request #536 from mikeshulman/lemma6.2.8

cite 2.11.3 and 2.11.5 in 6.2.8, close #527
mark errata