[Doc] Document DOM nodes in readme

[KHCode]

I'm trying to understand the object that HTMLParser.parse() returns and I can't seem to find the schema in your README file. Am I just not seeing it? I currently have to use a bunch of console.logs to figure out what is inside this object.

[KHCode]

You know what, I reread the docs and I think all you're missing is a link to the MDN docs for DOM tree, I think that would be helpful.

[taoqf]

pr is welcomed