ok, starting this: turn bogus <em> to <var>

ok, starting this: turn bogus <em> to <var>
also:
- several markup improvements (I hope)
- remove &nbsp; from c&p examples, because:
  - if you want preformatted text, use <pre>
  - they may lead to invisible errors (\xA0 = &nbsp;
    is not recognized by the config parser as whitespace)

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@97069 13f79535-47bb-0310-9956-ffa450edef68