* Fixes warnings in RST file
* Suppress warning log from pyeclib during the doc build.
pyeclib emits a warning message on an older liberasurecode [1]
and sphinx treats this as error (when warning-is-error is set).
There is no need to check warnings during the doc build,
so we can safely suppress the warning.
This is a part of the doc migration community-wide effort.
http://specs.openstack.org/openstack/docs-specs/specs/pike/os-manuals-migration.html
[1] https://github.com/openstack/pyeclib/commit/d163972b
Change-Id: I9adaee29185a2990cc3985bbe0dd366e22f4f1a2