Docs: Added missing period

[mosse]

The second paragraph under plugins.js has had a missing period added at its end:

One approach is to put jQuery plugins inside of a (function($){ ... })(jQuery); closure to make sure they're in the jQuery namespace safety blanket. Read more about jQuery plugin authoring.

[patrickkettner]

anyone who takes their time to create a pull request for a single letter typo in docs is friggin awesome in my book.

thanks a ton, @mosse!

[mosse]

Every little helps, right? :)

[arthurvr]

Thanks @mosse!