Better markdown support

[D4R5 C0D3]

In order to write a good CONTRIBUTING.md we would need better markdown support.

I tried to format my CONTRIBUTING.md a bit more fancy so that it's easier to read and and help convey the information better, but this plugins breaks down left and right when you do so. A CONTRIBUTING.md is already a pretty boring document but at the same time very important, having proper markdown support will improve the read ability of the document. Forcing us to only use headers and a single block below each h1 and h2 header is not going to cut it.

Here are some points that could improve this plugin:

• Display the text that is put before the first h1 as this might have some general information.
• add H3 support to create smaller sub sections
• list support in h1 ( currently bullets work but mark up is broken IMO )
• Allow for multiple block elements in h1, h2 and h3 when supported
• Allow reference links to be used, inline links are prone to error when u have to change a single url with in a document.

If there is no desire to improve the allowed markup in the CONTRIBUTING.md I would suggest using a differed filename for this plugin since this file is a defacto for very important information.

I attached a CONTRIBUTING.md which show where the markdown breaks.