[Docs] Kahu Documentation update for the usage of backend and all other features

[skdwriting]

Issue/Feature Description:
Kahu Documentation update for backup usage information. Current user guide talks only about basic features of backup and restore. It can provide the information related all the backends and other features how to use and experience
Why this issue to fixed / feature is needed(give scenarios or use cases):
Experience all features supported
How to reproduce, in case of a bug:
NA
Other Notes / Environment Information: (Please give the env information, log link or any useful information for this issue)
NA