Added feature detection example

[yoavweiss]

Closes #7

@igrigorik - Can you take a look?

[yoavweiss]

PRed the example in DOM. Will link to it from here once it's in.

[igrigorik]

Great, thanks!

[toddreifsteck]

LGTM

[igrigorik]

@yoavweiss what's the resolution here? are we going to drop in a non-normative note to link to the example?

[yoavweiss]

The example in DOM as currently suggested may not be of great value to developers in my view.

So, we can link to an external example and/or simply write a short blog post that would explain the use of supports().

[igrigorik]

@yoavweiss let's add a non-normative note in the spec and link to the gist (which, btw, should probably be .html to get the syntax highlighting). Once you have a blog post you can link it from the gist as well.

[igrigorik]

@yoavweiss looks like the HTML spec PR landed, can we update this and resolve it? :)

[igrigorik]

Closing, resolved via #52.