Problems with configuration for externalization of sessions to JDG

The docs on externalizing sessions to JDG is duplicated in various versions of the JDG and EAP docs. Most of them are very wrong. They all need updated to be the same and correct.
(or else removed and point to a single place where it's documented correctly).

The EAP 7 version appears to be correct (using invalidation-cache instead of replication-cache, not setting preload="true", using the existing web cache container instead of creating a new one). But the EAP 6 and JDG versions all have these major problems.

Note that there are minor differences in EAP 6 vs 7 configuration, such as batching="true" vs <transaction mode="BATCH"/> so those will be slightly different. The JDG version of the docs should point these out depending on which EAP version you're configuring it for.