Add Edge to the jQuery core support matrix

[dmethvin]

We're testing on Edge (see http://swarm.jquery.org/project/jquery) but don't have it listed at https://jquery.com/browser-support/ . The layout there is getting rather wide, maybe we should go to a vertical layout.

/cc @jacobrossi

[mgol]

I wouldn't introduce any major changes here as all that is handled in the jquery-3 branch, see #111 (comment).

I'll just add an Edge column for now. I can merge Chrome with Firefox as they have the same support strategy so the number of columns won't increase.

[mgol]

The page has been updated.

[dmethvin]

Thanks @mzgol!