Add guide for configuring messaging in high availability for Wildfly

[mnovak1]

Issue https://github.com/wildfly/wildfly.org/issues/623

Link to generated guide (located in my space)::
https://mnovak1.github.io/guides/messaging-high-availability

[mnovak1]

I have a question : you didn't define the connection factory or pcf to the cluster which should use the connectors to each broker

@ehsavoie Actually it's not needed as once the connection factory or pcf creates connection to any broker, it receives topology of the whole cluster (even in case of in-vm connector in pcf). So it will know where the backup is and load balance all new connections to active brokers in cluster.

[bstansberry]

@ehsavoie Is this ok now?

Once approved please comment in https://wildfly.zulipchat.com/#narrow/stream/274477-Pull-requests/topic/wildfly.2Eorg.20PRs so we know to process it.

[mnovak1]

I've fixed the merge conflicts and repushed.

[bstansberry]

Thanks @mnovak1!

[mnovak1]

Thanks @mnovak1!

@bstansberry @ehsavoie Thank you for your time and effort in reviewing my pull request. I really appreciate it!