add note re: handling events in capture phase

Couldn't find any mention in the documentation on how to handle events during the capture phase. I added a sentence in the events documentation to explain the "...Capture" syntax. Feel free to move the explanation elsewhere.
I think this sounds pretty good. Just a little tweak:

1. Let's use backticks around the event names so they use code formatting
2. "(for example: onClick -> onClickCapture)" can be it's own sentence. "Instead of using `onClick`, you would use `onClickCapture` to handle the click event in the capture phase" ... or something like that.