Documentation: improve code block titles and notes CSS
Documentation: improve code block titles and notes CSS

The title of code blocks and notes had no CSS style at all. So they
looked like any other normal text around.

Now, code blocks and notes look much closer to how native asciidoc
renders them. This change also outdents code blocks.

Test plan:
  $ buck build docs
  $ open buck-out/gen/Documentation/searchfree__tmp/Documentation/intro-user.html
Check how notes and code block titles are rendered.

Change-Id: Iae5d5a77dcb9a1d4b94073f742b1446381256845

WANdisco/gerrit,GerritCodeReview/gerrit,MerritCR/merrit,WANdisco/gerrit,joshuawilson/merrit,qtproject/qtqa-gerrit,WANdisco/gerrit,WANdisco/gerrit,gerrit-review/gerrit,GerritCodeReview/gerrit,qtproject/qtqa-gerrit,MerritCR/merrit,MerritCR/merrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,gerrit-review/gerrit,MerritCR/merrit,WANdisco/gerrit,WANdisco/gerrit,qtproject/qtqa-gerrit,GerritCodeReview/gerrit,MerritCR/merrit,GerritCodeReview/gerrit,MerritCR/merrit,qtproject/qtqa-gerrit,joshuawilson/merrit,gerrit-review/gerrit,GerritCodeReview/gerrit,MerritCR/merrit,joshuawilson/merrit,MerritCR/merrit,WANdisco/gerrit,qtproject/qtqa-gerrit,joshuawilson/merrit,gerrit-review/gerrit,gerrit-review/gerrit,gerrit-review/gerrit,GerritCodeReview/gerrit,qtproject/qtqa-gerrit,joshuawilson/merrit,gerrit-review/gerrit,qtproject/qtqa-gerrit,joshuawilson/merrit,joshuawilson/merrit,joshuawilson/merrit