AS/WildFly documentation should reside in AS/WildFly documentation

Even though this is somewhat convenient for the documentation to reside in modcluster documentation, i.e. here http://docs.jboss.org/mod_cluster/1.2.0/html_single/#java.AS7config , it should indeed reside in the correct space which is the AS/WildFly documentation, i.e. here https://docs.jboss.org/author/display/WFLY8/mod_cluster+Subsystem .

The current structure is not correct, since the same version of modcluster is used in the same version of WildFly (e.g. 1.3.0 being used in WildFly 8 and 9) but the subsystem configuration is different.

This will also enable us document things quickly at the time of changing and correspond to the right version. We could link the documentation so it will still be easy to find.