Update "Handling Ip Address Change" documentation to include changing the /opt/couchbase/var/lib/couchbase/ip* file.

The current documenation shows the following steps for using hostnames/ ip address change w/ couchbase http://www.couchbase.com/docs/couchbase-manual-2.0/couchbase-bestpractice-cloud-ip.html.

The /opt/couchbase/var/lib/couchbase/ip* contains the actual ip address of a node, once its a part of a cluster.

When the node is renamed using hostnames, this file is NOT automatically updated. We see failures while doing simpler tasks like
-upgrade from version X to version Y ( refer bug http://www.couchbase.com/issues/browse/MB-7241)

The current workaround on this is manually editing the /ip file after updating the hostname to "hostname" as referenced in the /opt/couchbase/bin/coucbase-server.

The documentation for using hostnames should be updated accordingly.

• Additional Step : Update the /opt/.../ip file to "your_hostname".