Make the upgrading doc more user-friendly by explicitly

stating some places where things *haven't* changed.

The statement about third-party modules could use some
review by someone who has tried some.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@349741 13f79535-47bb-0310-9956-ffa450edef68