[whatwg] Dom as Audience Prereq

[Smylers]

The audience section states familiarity with Dom Core and Dom Events as
prereqs for reading the HTML 5 spec:

  http://www.whatwg.org/html5#audience

As somebody without this Dom background there are certainly many parts
of the spec which I've found both understandable and useful (to a web
author).

There may be parts which do require Dom knowledge, but as written it
sounds like a prereq for understanding any part of the spec, and as such
may unnecessarily put people off.

Smylers