Making doc fixes in backup-snapshots.rst
Making doc fixes in backup-snapshots.rst

Fixing grammar, adding missing new lines and code blocks, spelling fixes etc.

TrivialFix
Change-Id: I750e91e6f81ced1dad039a51663da919501bf29f
Signed-off-by: Nitin Madhok <c8174d7992f097a3f2d24d7440ec693062ae568f@g.clemson.edu>

openstack/cinder-specs