DOCS: Create standard for format and structure of top-level project files across AboutCode repos

In most AboutCode repos we have a set of top-level project files including:

- AUTHORS.rst
- CHANGELOG.rst
- CODE_OF_CONDUCT.rst
- CONTRIBUTING.rst
- LICENSE
- NOTICE
- README.rst
- RELEASE.md (dejacode and scancode.io)
- ROADMAP.rst

I looked at dejacode, purldb, scancode.io. scancode-toolkit and vulnerablecode as the primary examples

Although the GitHub norm is for the these files to be in markdown format we are using rST in most cases so the cost/effort to move to markdown does not make sense at this time.

For the LICENSE and NOTICE files we have a mixed bag:

- dejacode: LICENSE file but no NOTICE (makes sense for AGPL-3.0 vs Apache-2.0)
- purldb: NOTICE file plus apache-2.0.LICENSE and cc-by-sa-4.0.LICENSE
- scancode.io: LICENSE and NOTICE files - this should be the pattern for all projects licensed under Apache-2.0)
- scancode-tookit: NOTICE file plus apache-2.0.LICENSE and cc-by-4.0.LICENSE
- vulnerablecode: NOTICE file plus apache-2.0.LICENSE and cc-by-sa-4.0.LICENSE

If you have a top-level file named LICENSE GitHub displays the license name in a "tab" at the top of the README. Using LICENSE as the file suffix does not seem to mean anything to GitHub.

The issue here is to standardize the format and structure of these files across repos and document it for new projects/repos. Some immediate action items include:

- [ ] Convert RELEASE.md files to rST for dejacode and scancode.io (this should be easy since these are small chunks of text)
- [ ] Rename apache-2.0.LICENSE files to LICENSE.