docs(contrib): add initial COLLABORATORS guide (#4158)

Author: seanmonstar

docs/COLLABORATORS.md

@@ -0,0 +1,68 @@
+# hyper Collaborator Guide
+
+This document describes how collaborators manage hyper.
+
+- First off, a collaborator doesn't need to do all of the following perfectly.
+	- It takes time to learn.
+	- Instead, focus on growth.
+	- Get in the habit of checking this guide with some frequency, and improve rather than stagnate.
+
+## Exemplify the Code of Conduct
+
+- Our [code of conduct](./CODE_OF_CONDUCT.md) is not elaborate. It doesn't require much study, nor explication.
+- To be a good collaborator, it does require internalizing it.
+- The code of conduct is proactive, positive.
+- A collaborator must be a good example of being kind.
+	- It should not be possible to find significant fault in a collaborator against the simple principles in the code of conduct.
+
+## Internalize the Vision
+
+- Understand and use the project's [vision](./VISION.md) when helping guide decisions.
+
+## Review Pull Requests
+
+- Review pull requests promptly and kindly. Approve CI for new contributors.
+	- Consider telling a maintainer to add you to the automated review queue.
+- Collaborators should feel comfortable approving and merging straightforward changes. Such as documentation, chores, styling, simple refactors, and basic bug fixes.
+- When reviewing larger changes, keep in mind the points on [being API caretakers](#api-caretakers).
+- When approving a PR, allow time for other collaborators to look before merging.
+	- Especially if the PR is newer, or has a more significant change.
+- When merging, prefer squashing (it adds in the PR number). Touch up the commit message to match our [COMMITS](./COMMITS.md) style.
+
+## Provide Feedback on Features and Designs
+
+Collaborators try to participate early and often when new features are proposed. They also actively consider and recommend new features that users may need.
+
+### API Caretakers
+
+Collaborators are caretakers of hyper's API. When proposing, discussing, or reviewing changes to hyper, keep the following in mind:
+
+- Conservative additions
+	- Conservative APIs reduce breaking changes
+- Don't expose internal implementation details
+	- [Accessors can reveal internal repr](https://seanmonstar.com/micro/20260721-accessors-reveal-internal-repr/)
+- hyper-util is a place to explore first
+	- [Vision: Not quite stable, but utile](./VISION.md#not-quite-stable-but-utile-useful)
+	- [Roadmap: hyper-util](./ROADMAP.md#hyper-util)
+- Unstable features
+	- Unstable features are not bound by our stability promise.
+	- We don't just name a crate feature with unstable.
+		- This has the problem of an intermediary crate enabling it, and someone depending on _that_ crate and not realizing they are accessing unstable hyper features.
+	- All unstable features require a conditional config flag passed to the Rust compiler.
+		- For example, `hyper_unstable_ffi`.
+- Breaking changes
+	- These would usually be reserved for a new SemVer major release, such as v2.0, and thus would usually be very rare.
+	- An exception is fixing a mistake quickly after release of a new feature.
+	- All breaking changes require approval by a maintainer.
+
+## Welcome New Contributors
+
+- Help new contributors find their way around the project and its processes. Follow the guidance on [acknowledging people when triaging](./ISSUES.md#acknowledge).
+
+## Answer Questions
+
+- Answer questions in issues or chat when you can, or help find someone who can. See the project's [help channels](../CONTRIBUTING.md#help).
+
+## Mentor Contributors
+
+- Help contributors grow toward becoming project members. Issue triaging often provides opportunities for [mentoring](./ISSUES.md#mentoring), but the ideas can be applied to reviews, or when answering questions.

docs/GOVERNANCE.md

@@ -71,6 +71,7 @@ How to become:
 ### Collaborator
 
 Collaborators are contributors who have been helping out in a consistent basis.
+See the [collaborator guide](./COLLABORATORS.md) for practical guidance on the role.
 
 Responsibilities: