[whatwg/dom] Add a section on defining a new event (#364)

Needs to cover:

* Brief description on inheritance of dictionaries and interfaces
* Using present tense for Event/type
* Event/type being all lowercase without hyphens
* Pointers to "fire", "create", and "dispatch" (and handling return values of fire and dispatch)

Anything else?

(This might involve moving some information around. I'd rather not say the same twice.)

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/whatwg/dom/issues/364