am 939c3f72: docs: modify css to support sidenav headings with span, instead...

am 939c3f72: docs: modify css to support sidenav headings with span, instead of h2 because I suspect the h2 is sending mixed signals to search engines for result snippets

* commit '939c3f72':
  docs: modify css to support sidenav headings with span, instead of h2 because I suspect the h2 is sending mixed signals to search engines for result snippets