documentation for _update and _applyDataApi

[rtpHarry]

Would be useful to add a little note in the docs about _applyDataApi().

https://github.com/liabru/jquery-match-height/blob/master/jquery.matchHeight.js#L305

In my experience, I had an infinite scrolling grid, and calling _update didn't fix the newly loaded elements.

I had set them up using the data-mh api in the CMS.

Calling $.fn.matchHeight._applyDataApi(); did do the trick, though.

And perhaps adding a note to the _update to say this is also an option.