Consider Node Markdownlint

[GarthDB]

I've been using markdownlint and the project that started as a node port by @DavidAnson.

I've found the node version to be more useful - the frontMatter alone has saved me a lot of headaches.

The node project is also more active. I've made 2 pull requests to the ruby version (one of which to add similar frontMatter functionality, but haven't heard anything yet. The last accepted pull request was on Apr 6.

[wjdp]

Front matter support would be fantastic, the main reason I've stopped using this linter