Merge r1783722, r1783723 from trunk:

Fix ProxyPassReverse schemes in mod_proxy_http2's doc (examples).

build doc.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1783726 13f79535-47bb-0310-9956-ffa450edef68