fix some style issues

- red solid border around warning areas
- <syntax> gets a <code> around
  (more shouldn't be used, because it breaks the flow too much)
- headings of warnings, notes & examples are left aligned

Based on a Proposal by: Tim Gerundt <tim@gerundt.de>

Added some linebreaks for better diffs... ;-)


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@97133 13f79535-47bb-0310-9956-ffa450edef68