evil: make it clear in the docs that this library is private to efl
Since the 1.23 release we are stricter with the use of evil. It is
supposed to be used inside efl only and not exposed as API. Make this
clear in the docs as well.
Reviewed-by: Vincent Torri <firstname.lastname@example.org>
Differential Revision: https://phab.enlightenment.org/D10295