am f2b544f5: am 337b0873: docs: update backup guide and bmgr tool elaborate...

am f2b544f5: am 337b0873: docs: update backup guide and bmgr tool elaborate the guide to testing a backup agent and add links between the docs

Merge commit 'f2b544f5ae7676f7ab4cdf3379b2ed3c60a65def' into gingerbread-plus-aosp

* commit 'f2b544f5ae7676f7ab4cdf3379b2ed3c60a65def':
  docs: update backup guide and bmgr tool