Support markdown in source code docs

[dherges]

Bug, feature request, or proposal:

Feature request / Proposal

What is the expected behavior?

It'll be nice to have markdown formatting in the documentation pages.

What is the current behavior?

No markdown.

What are the steps to reproduce?

E.g. https://material.angular.io/components/component/radio

What is the use-case or motivation for changing an existing behavior?

Better docs ⚡ 🌤️ 🌈

Which versions of Angular, Material, OS, browsers are affected?

n/a

Is there anything else we should know?

If of interest, I can start a PR. I did something siminilar in a project that took your dgeni configuration as a starting point. Requires some changes to the nunjucks templates.

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}