core.xml: revert turns to <pre>formatted examples and use

          <indent> elements
update transformations of core.html.en and
  quickreference.html.en (due to the mod_rewrite.xml fix)


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@97146 13f79535-47bb-0310-9956-ffa450edef68