merge r1637112 from trunk:

mention the cmake-based build


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1637114 13f79535-47bb-0310-9956-ffa450edef68
make docs

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1637115 13f79535-47bb-0310-9956-ffa450edef68
missed mergeinfo update from r1637114

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1637116 13f79535-47bb-0310-9956-ffa450edef68