Configuration Guide: missing documentation on how to externalize HTTP sessions to JDG

EAP 6 documentation had a chapter on how to externalize HTTP sessions to JDG [1]. This must be brought forward.

IMHO, this belongs somewhere inside chapter 17. Configuring High Availability, it shouldn't be a separate top-level chapter like in EAP 6.

It shouldn't be much work – the content from EAP 6 documentation is still mostly valid. These items require slight adjusting:

• the example in 1st step of Procedure 25.1. Externalize HTTP Sessions: version of the infinispan subsystem is now 4.0 and caches are configured slightly differently (see below)
• the text "Add passivation and cache information" in 4th step should be changed to "Add cache information"
• the example in 4th step: XML schema version must be changed (it's now jboss-web_10_0.xsd), <replication-trigger> and <passivation-config> must be removed (no longer supported)
• the note at the very end of the chapter must be removed (<passivation-config> no longer supported)

The example in step 1 of the EAP 6 documentation looked like this:

<subsystem xmlns="urn:jboss:domain:infinispan:1.5">
  [...]
  <cache-container name="cacheContainer" default-cache="default-cache" module="org.jboss.as.clustering.web.infinispan" statistics-enabled="true">
    <transport lock-timeout="60000"/>
    <replicated-cache name="default-cache" mode="SYNC" batching="true">
      <remote-store cache="default" socket-timeout="60000" preload="true" passivation="false" purge="false" shared="true">
        <remote-server outbound-socket-binding="remote-jdg-server1"/>
        <remote-server outbound-socket-binding="remote-jdg-server2"/>
      </remote-store>
    </replicated-cache>
  </cache-container>
</subsystem>

As far as I know, it should look like this for EAP 7 (there's quite a bunch of changes, but all of them are just syntax):

<subsystem xmlns="urn:jboss:domain:infinispan:4.0">
  [...]
  <cache-container name="cacheContainer" default-cache="default-cache" module="org.jboss.as.clustering.web.infinispan" statistics-enabled="true">
    <transport lock-timeout="60000"/>
    <replicated-cache name="default-cache" mode="SYNC">
      <locking isolation="REPEATABLE_READ"/>
      <transaction mode="BATCH"/>
      <remote-store remote-servers="remote-jdg-server1 remote-jdg-server2" cache="default" socket-timeout="60000" preload="true" passivation="false" purge="false" shared="true"/>
    </replicated-cache>
  </cache-container>
</subsystem>

But frankly, we should show how to configure this using CLI instead of showing XML snippets.

mgencur is responsible for this on the JDG QE side, so he should be able to answer all the JDG-related questions.

[1] https://access.redhat.com/documentation/en-US/JBoss_Enterprise_Application_Platform/6.4/html/Administration_and_Configuration_Guide/chap-Externalize_Sessions.html