Restore documentation of `Typeclasses Axioms Are Instances`
Restore documentation of `Typeclasses Axioms Are Instances`

This documentation seems to have been lost after it was introduced by
0ad26633a4589d77de1f864733d1d953dab9ea91

We also document that this flag is deprecated.

coq/coq,Zimmi48/coq,silene/coq,gares/coq,Matafou/coq,JasonGross/coq,Matafou/coq,Matafou/coq,SkySkimmer/coq,gares/coq,SkySkimmer/coq,ejgallego/coq,coq/coq,SkySkimmer/coq,coq/coq,ejgallego/coq,Zimmi48/coq,JasonGross/coq,JasonGross/coq,gares/coq,Zimmi48/coq,ejgallego/coq,gares/coq,silene/coq,Zimmi48/coq,SkySkimmer/coq,silene/coq,ejgallego/coq,gares/coq,JasonGross/coq,coq/coq