Add Proposed Draft Change Issue Template

[kyzer-davis]

• Added Issue Template (and Proposed Change tag) for capturing information on proposed text changes to ease authoring changes in the XML draft.
• Gave the readme a fresh coat of paint:
  • Way more links, mainly to discussions to hopefully avoid duplicate issues and encourage discussions in ongoing threads.
  • Expanded upon in scope, scoping, and out of scope items
  • Added contributing section.
• Added Github Pages at https://uuid6.github.io/uuid6-ietf-draft/ which is the HTML Draft 02 as a index.html file in the root folder. (Will flip this to the master branch when we merge this PR.) Furthermore, once we commit #58 I will flip this to reflect Draft 03.
• I also went through the issue tracker to re-open, re-title, tag, and create a discussion topic where relevant.
  • Those threads will remain open forever and discussions should be funneled to one of those to help keep things in a neat orderly.

[bradleypeabody]

@kyzer-davis do me a favor and make the example wording change for the issue template be from "MAY" to "SHOULD". Otherwise I'm good with it, go ahead and merge at your convenience.