README: fix formatting

[kanzure]

Markdown wasn't rendering the headings correctly.

[kanzure]

Only looks a little better. Still broken though.

[RandyMcMillan]

#166

@kanzure,
As you can see in my comments. The variations on markdown flavors has become ridiculous.
Having given it more though....maybe the atom editor conforms to gh flavored markdown.
as a vim user this is kinda annoying - but I guess to avoid these issues when committing to gh repos it will have to do. --peace!