Clarification of mod_access_compact and mod_authz_host usage.

Clarification of mod_access_compact and mod_authz_host usage.

A recent email in docs@ brought up an interesting use case, namely mixing
mod_access_compact (Order, Deny, Allow) and mod_authz_host (Require) directives
while migrating from 2.2 to 2.4. This is technically possible but it leads
to a lot of confusion due to how config merge works between these modules. This change adds
some examples on the documentation about things that might go wrong when mixing
old and new directives, stating clearly that mod_access_compact or mod_authz_host
should not be used together.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1738542 13f79535-47bb-0310-9956-ffa450edef68