Update HTTPS Everywhere Documentation (#19405)

* Update Documentation

- Create distinctions between users, contributors, and website owners
- Provide guide links for all 3
- Comply more with Google Markdown style
- Update Contributor guide and consolidate information

* Update CONTRIBUTING.md

Co-authored-by: pipboy96 <[email protected]>

* Add back tabs for XML example

Co-authored-by: pipboy96 <[email protected]>

Author: zoracon