CI: Rename yamllint config file

CI: Rename yamllint config file

Yamllint does not look for a yamllint.conf file and we're calling it
(that I can find) anywhere with an explicit config file definition.
Since .yamllint is the default file used, we are fixing the filename

Additionally, we are adding a section on comments to protect against the
prettier pre-commit hook that enforces a single space instead of
yamllints normal double space for comments after content

Change-Id: I0df4b467ea57b1558dbb3c71d74775f84a88b037
Signed-off-by: Andrew Grimberg <agrimberg@linuxfoundation.org>