HA: add more interesting info

Signed-off-by: David Scott <dave.scott@citrix.com>
HA: add more explanation

Signed-off-by: David Scott <dave.scott@citrix.com>
Add a reference to js-sequence-diagrams

Signed-off-by: David Scott <dave.scott@citrix.com>
HA: more explanation

Signed-off-by: David Scott <dave.scott@citrix.com>
HA: add a few links to source code

Signed-off-by: David Scott <dave.scott@citrix.com>
Merge pull request #15 from djs55/more-ha

More HA stuff