Feature/revise spec

DO NOT MERGE. FOR DISCUSSION ONLY. @zdne @honzajavorek Please comment.

This PR updates the SPEC based on @zdne and my multiple discussions and refinements.

It also pulls in the current README with some typo fixes. 

@zdne I basically forked and update your branch for this PR into master. Would you prefer I just fork off of master and just create a branch the only adds the spec? Let me know.
I would think so. From my discussions with @zdne, the spec will be parsed as written and tooling will enforce best practices/rules etc. We have highlighted some recommendations for that in the Inheritance section, but those will not be enforced by the parser.