Add a best practices list

[jrhorn424]

Some things to include:

• prefer .on('click') to .click()
• prefer $.ajax() with the deferred object interface (don't use $.get and friends since it use arguments instead of "promise")

[payne-chris-r]

@jrhorn424 I'm happy to add this, and think I mentioned it last time, but I'd love to put a solid reason behind why .on('click',...) > .click() in the README if possible.

[jrhorn424]

Pedagogically, it gets them thinking about events. It's less magic. More importantly, we can't take advantage of bubbling to event delegation with click. Compare the signatures:

1. https://api.jquery.com/click/
2. http://api.jquery.com/on/