Feature/update documentation

@cabbott @chad-medi Since you have been the implementers so far, please review. Also, @brutski please chime in.

Contains:
* Updated README with links to reference other documents
* Updated resource_descriptors.md due to moving some info around
* Updated gemspec to align with README

What it does note contain:
* Updated documentation in some of the referenced YARD documentation. Will do in another PR.
I agree with Crichton here.