format-code: enable markdownlint

Enable markdownlint but allow it to always pass.  This will allow
maintainers the opportunity to run the tools and fix up their own
markdown before we enable this globally.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ie397a72ca4ef113cdbe433d263ccf3bd5063cf4b
6 files changed