configure markdown lint

[BillWagner]

First configuration of markdown lint. We can determine which warnings we want to enable or disable from a first test run.

We can adjust what's reported by adding items from the markdown lint rules.

[BillWagner]

@jskeet Here's a PR that turns on markdown lint in our repo.

Over time, it's probably a good idea to have it on with most warnings enable. I already turned off 2 by design:

• Warning on inline HTML
• Warning on long lines

We use both of those intentionally.

Take a look at the warnings. See which ones are most helpful to get our markdown source to work well with the word converter.

Then, we can figure out a plan.

[jskeet]

All the current warnings look good to me - thanks!

[BillWagner]

@jskeet

I'm think of this as a plan:

• I'll update this PR to disable every current warning (due to the noise).
• Once this is merged, I'll make PRs to re-enable each warning (or a set) and resolve each of those warnings.

[jskeet]

Works for me :)

I want to verify a couple assumptions.

[BillWagner]

@jskeet This is ready for final review. I want you to take a look because of some of rules changes:

A couple note on the 4th commit:

MD034 is for "raw URL link". The standard contains the link to the ECMA site, which is intentional. If it helps the word converter, that can be formatted using markdown's []() syntax.

MD30 and MD31 will be the two biggest jobs.

Also, some of the warnings are generated from the markdown source in the test project. I think the right move will be to update those test sources once the associated rules are enabled.

[jskeet]

I'll look at this on Monday if that's okay - my weekend is pretty busy.

[jskeet]

Yup, this feels like a good approach to me.