bug#17309: 24.4.50; Typos in autotype info

[Drew Adams]

> >      "Iff" means "if and only if".  This terminology comes from
> >      mathematics.  Try to avoid using this term in documentation, since
> >      many are unfamiliar with it and mistake it for a typo.
> 
> Indeed, I think "iff" is perfectly fine in docstrings, but we should
> refrain from using it in the Texinfo documentation.

FWIW, a different policy was decided and followed before:
http://lists.gnu.org/archive/html/emacs-devel/2007-08/msg00306.html

Why this policy change now?