[ovs-dev] [RFC] make: Add 'lint-docs' target

[Finucane, Stephen]

> This provides a quick, easy way to use the 'mdl' executable provided
> in markdowlinter to validate documentation.
> 
> This change does not resolve any of the issues this linter raises -
> these will need to be done in a follow up patch.
> 
> Signed-off-by: Stephen Finucane <stephen.finucane at intel.com>

This is strictly an RFC. I'm interested in the idea of automating validation
of documentation. While we can't validate the content itself, we can certainly
extract meaning from the docs. For example:

    1. do something like so:
      echo "hello, world"
    2. run something else

We should be able to figure out that this is code, and that it's not been
properly indented. How we do that (this tool or otherwise) is up for debate.

Cheers,
Stephen