Docs bots email

Galina, folks,

It seems the document buildbots are not sending emails, and they keep
going back to red.

http://lab.llvm.org:8011/builders/llvm-sphinx-docs
http://lab.llvm.org:8011/builders/clang-sphinx-docs
http://lab.llvm.org:8011/builders/lld-sphinx-docs
http://lab.llvm.org:8011/builders/libcxx-sphinx-docs

Given that the server is setup in the same way (-Werror), whenever the
bot is red, means the website is *NOT* updated. It stands to reason
that we can't let that bot go red.

Did we disable them on purpose? Can we go back sending emails?

cheers,
--renato