More Comprehensive guide for Swift deployment on multinode

[SHASHANK TAVILDAR]

The following guide: http://docs.openstack.org/developer/kolla/swift-guide.html
which explain swift installation with kolla should also have a section for multinode installation.
More specifically:
1. Mention the host(storage/deployment) on which to execute the script for creating rings and for adding nodes to ring.
2. There must also be a note of creating swift config directory before running the swift installation playbooks: mkdir -p /etc/kolla/config/swift/backups.
3. The guide should also mention that swift client needs to be installed on deployment host to create ring since swift-ring-builder requires swift python client.