Rm false-pos-prone rst linting, rely on Sphinx

Rm false-pos-prone rst linting, rely on Sphinx

Remove Coala RSTcheckBear and reSTLintBear reStructuredText linters.

They both cause lots of false positives because they are not aware of
Sphinx-specific syntax. We already get good coverage by setting Sphinx
to fail on warnings. The main docs project did the same change in 69906.

Change-Id: I287b3cabcd10b376994c1fcdc9de3da94ddb73dd
Signed-off-by: Daniel Farrell <dfarrell@redhat.com>