Browser compatibility list in readme.md

[esteinborn]

Can you add the browser compatibility list to the readme?

EX:

Browser Compatibility

IE - 7+

[eligrey]

If you can compile a comprehensive list with the minimum versions for IE, FF, Chrome, and Safari, I will accept a pullreq.

[esteinborn]

do you have a browser list that you were programming for to start from?

[eligrey]

Only that it worked in current versions of FF, Safari, Chrome, and IE (8) at the time of initial commit. If I had a minimum version list then there would already be a compatibility table :P

[esteinborn]

Ok, so I can start with IE8 :). thanks.