Updated README.MD and included links to docs/contributing.md and also docs/example-app.rb

The contributing files have been added as a guide to building a new part.O
removed getting started header
formatting issues fixed in example-part.rb
renamed md to rb for example
Updated README.MD and included links to docs/contributing.md and also docs/example-app.rb

The contributing files have been added as a guide to building a new part.O
Updated example docs per Lakshan's advice.

Workflow has been added to contributing.md
comments in example-part.rb have been clarified.