Adds MD010 (Hard tabs), MD012 (blank lines), MD029 (ordered
list prefix), MD030 (spaces after list markers), and fixes
remaining docs that were failing these tests
Many code blocks are 4spaced, and they render in GitLab
without coloring as a result, even though they are
fenced with a language label. If in a list, other items
will render as being in a code block too, even if not
meant to. This fixes all these issues for many admin
docs in /high_availability and /auth (part 1)
Many users were unable to get logins working with OpenID Connect because
of a missing `name` argument in the configuration. This resulted in 404s
immediately after attempting to login. This describes the workaround
mentioned in
https://gitlab.com/gitlab-org/gitlab-ce/issues/62208#note_178774809.
This also adds an example profile for using Google.
