Split CONTRIBUTING.md: separate contributor and maintainer docs, add etiquette guidelines

[Copilot]

The existing CONTRIBUTING.md conflated contributor and maintainer instructions. This change separates concerns and adds explicit etiquette guidelines for new contributors.

Changes

• Created MAINTAINERS.md: Extracted maintainer-specific content (PR ownership, assignee responsibilities, triage process)

• Updated CONTRIBUTING.md: Added "Contributor Etiquette" section with:

  • Don't open competing PRs for issues already assigned/being worked on
  • Request assignments thoughtfully (not dozens at once)
  • Demonstrate understanding when requesting assignment: summarize the challenge, propose approach, identify files to modify, ask questions
  • Use AI tools for research assistance, but explain ideas in your own words rather than copy-pasting

Example

New contributor etiquette in action:

### Requesting Issue Assignments
- **Quality over quantity**: Please do not ask to be assigned to dozens of issues at a time.
- **Demonstrate understanding**: When requesting to be assigned to an issue, show that you understand the problem by including:
  - A summary of the challenge or bug
  - Your proposed approach to solving it
  - Which files or components you plan to modify
  - Any questions you have about the implementation

Original prompt

Currently, our CONTRIBUTING.md guide conflates instructions for contributors and maintainers.

Can you please split this into two files? One for CONTRIBUTING.md and one for MAINTAINERS.md?

Something we'd like to clarify in CONTRIBUTING.md is etiquette and process for new contributors.

For instance:

1. If someone has asked to work on an issue, please try to exercise good ettiquite by not going out of your way to open a PR for that issue in a way that undermines this contributors effort.
2. Please do not ask to be assigned to dozens of issues at a time -- instead put effort into your request for assignment. Contributors should demonstrate in their request to be assigned that they understand the challenge, the approach, which files to update, and any questions they have as a prerequisite or alongside a request to be assigned. This is also a great opportunity for using LLMs to assist with research (the contributor should not just regurgitate AI slop into their comment; no offense).

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[Copilot]

Pull Request Overview

This PR reorganizes documentation by moving maintainer guidelines to a dedicated file and adds contributor etiquette guidelines. The changes improve documentation structure and set clearer expectations for community contributions.

Key changes:

• Created a new MAINTAINERS.md file to separate maintainer-specific guidelines from contributor documentation
• Added a new "Contributor Etiquette" section in CONTRIBUTING.md with guidelines on respecting other contributors' work and requesting issue assignments
• Moved the "Maintainers" section from CONTRIBUTING.md to the new MAINTAINERS.md file

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
MAINTAINERS.md	New file containing maintainer guidelines for PR ownership and responsibilities, extracted from CONTRIBUTING.md
CONTRIBUTING.md	Added contributor etiquette section and removed the maintainers section (now in MAINTAINERS.md)

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