Added trove backup section to user guide
Added trove backup section to user guide

The trove chapter in the user guide did not have
a section on database backup and restore.

This commit covers how to backup and restore a
database instance.

This commit is a partial implementation of the blueprint.

Change-Id: If0457f6205f3bb98eddd8c72d6c7afd1e6327712
blueprint: user-guide-trove-chapter

AlekhyaMallina-Vedams/openstack-manuals,potsmaster/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,saeki-masaki/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,kairoaraujo/openstack-manuals,potsmaster/openstack-manuals,saeki-masaki/openstack-manuals,gongysh2004/openstack-manual,openstack/openstack-manuals,kairoaraujo/openstack-manuals,Akasurde/openstack-manuals,Akasurde/openstack-manuals,gongysh2004/openstack-manual