Since we're building out roles in system-config now, generate
documentation. We look in roles/* and playbook/roles/* (follow-on
changes will split things up between the two).
Correct the reference names in the exim documentation to avoid
warnings and failure.
This also revealed a single unicode character in the exim readme
(which caused prior versions of zuul-sphinx to barf). For fun, see if
you can find it!
Depends-On: https://review.openstack.org/#/c/579474/
Change-Id: I243a96bbd6d09560f8aa80b6345b90039422547a
b99c4c6fb0