Updates to the Maintainers Guidelines and list of Maintainer Tasks

[swcurran]

Signed-off-by: Stephen Curran swcurran@gmail.com

Updates the maintainers guidance document and adds a Sample MAINTAINERS.md file.

• Acknowledges that a MAINTAINERS.md file applies to a repo vs. a project.
• Talks about scope in terms of GitHub roles, or unrelated to GitHub Roles.
• Provides a sample Maintainers file.
• In the Sample Maintainers file, provides a list of tasks for open source software repository maintainers.

While I think this clarifies the Maintainer process and meaning, a key contribution is the tasks of an open source maintainer.

[swcurran]

Changes based on feedback applied, except about vetoes. Perhaps a quick discussion at the TOC meeting?

[swcurran]

Per the 2023.03.09 TOC Meeting, changes made:

• Veto removed from adding, removing maintainer in sample file.
• Added note for closing an unapproved PR to the maintainers file in sample file.
• Added Maintainer duty to sample MAINTAINERS.md about a reported security vulnerabilities.
• Added note and example in sample MAINTAINERS.md file for referencing a common Project maintainers file.

Ready for another review.

[swcurran]

Updated the text in the Guidelines about what must be populated and why in the Maintainers table.

[swcurran]

w00t!