Update contribution guidelines for pull requests

[lucassaldanha]

PR Description

We have had many instances where “random” potential contributors submit PRs for areas unsolicited and without prior discussion, etc.

This is similar to what we saw a few years ago during the golden age of Airdrops. We even added a section explicitly outlining the types of PRs we would not accept, to prevent airdrop farming.

With the wide adoption of AI on development, we are likely to see more and more contributions to Teku, what puts us under pressure for reviews etc.

The changes to our CONTRIBUTING.md document are not meant to discourage people from contributing, but to ensure that us, maintainers, can keep up with the demand for reviews, while maintaining the quality of our codebase.

Here is a summary of some research I did on other projects with similar criteria, and some essays on this topic:

• https://github.com/ghostty-org/ghostty/blob/main/CONTRIBUTING.md
• https://curl.se/dev/contribute.html
• https://github.com/melissawm/open-source-ai-contribution-policies
• https://nesbitt.io/2026/02/13/respectful-open-source.html
• https://codenote.net/en/posts/oss-ai-slop-contribution-policy-shift/

Fixed Issue(s)

N/A

Documentation

• I thought about documentation and added the doc-change-required label to this PR if updates are required.

Changelog

• I thought about adding a changelog entry, and added one if I deemed necessary.

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Note

Low Risk
Documentation-only change to contribution policy; no runtime, security, or build impact.

Overview
CONTRIBUTING.md now states explicitly that pull requests must be linked to an issue labeled good first issue or help wanted, or to work a maintainer assigned to you. It adds a short workflow (open an issue → wait for triage → then open a PR) and says unrelated PRs will be closed with a pointer to that section, framed as managing review load rather than rejecting contributors.

The former inline “airdrop farming” notes are grouped under a Airdrop Farming subsection. That list is reframed as examples that may be rejected even after an issue is opened, with small copy edits (e.g. “first-time”, “substantive”).

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