refactor(root): relocate the contributing guide into .github/

.github/CONTRIBUTING.md

@@ -0,0 +1,85 @@
+<!--
+SPDX-License-Identifier: CC-BY-SA-4.0
+Copyright (c) Jonathan D.A. Jewell <j.d.a.jewell@open.ac.uk>
+-->
+
+# Contributing to AcceleratorGate.jl
+
+This document explains how to contribute to the project. We follow a
+"Dual-Track" architecture where human-readable documentation lives in
+the root and machine-readable policies live in `.machine_readable/`.
+
+## How to Contribute
+
+We welcome contributions in many forms:
+
+- **Code:** Improving the core verified stack or extensions.
+
+- **Documentation:** Enhancing AsciiDoc manuals or AI manifests.
+
+- **Testing:** Adding property-based tests or formal proofs.
+
+- **Bug reports:** Filing clear, reproducible issues.
+
+## Getting Started
+
+1.  **Read the AI Manifest:** Start with `0-AI-MANIFEST.a2ml` (if
+    present) to understand the repository structure.
+
+2.  **Environment:** Use `guix` `develop` or `direnv` `allow` to set up
+    your tools.
+
+3.  **Task Runner:** Use `just` to see available commands (`just`
+    `--list`).
+
+## Development Workflow
+
+### Branch Naming
+
+    docs/short-description       # Documentation
+    test/what-added              # Test additions
+    feat/short-description       # New features
+    fix/issue-number-description # Bug fixes
+    refactor/what-changed        # Code improvements
+    security/what-fixed          # Security fixes
+
+### Commit Messages
+
+We follow [Conventional Commits](https://www.conventionalcommits.org/):
+
+    <type>(<scope>): <description>
+
+    [optional body]
+
+    [optional footer]
+
+Types: `feat`, `fix`, `docs`, `test`, `refactor`, `ci`, `chore`,
+`security`.
+
+## Reporting Bugs
+
+Before reporting:
+
+1.  Search existing issues.
+
+2.  Check if it is already fixed in `main`.
+
+When reporting, include:
+
+- Clear, descriptive title.
+
+- Environment details (OS, versions, toolchain).
+
+- Steps to reproduce.
+
+- Expected vs actual behaviour.
+
+## Code of Conduct
+
+All contributors are expected to adhere to our ethical standards. See
+[CODE_OF_CONDUCT](CODE_OF_CONDUCT.adoc) for details.
+
+## License
+
+By contributing, you agree that your contributions will be licensed
+under the same license as the project (see [LICENSE](LICENSE)).

MAINTAINERS.adoc

@@ -62,4 +62,4 @@ For questions about project governance:
 
 * link:GOVERNANCE.adoc[Governance Model]
 * link:CODE_OF_CONDUCT.md[Code of Conduct]
-* link:CONTRIBUTING.adoc[Contributing Guide]
+* link:.github/CONTRIBUTING.md[Contributing Guide]

docs/accessibility/README.adoc

@@ -244,7 +244,7 @@ Burble is committed to:
 * Supporting screen readers and other assistive technologies
 * Continuous improvement based on user feedback
 
-We welcome contributions to improve accessibility. See our link:../CONTRIBUTING.adoc[Contributing Guide] for details.
+We welcome contributions to improve accessibility. See our link:../../.github/CONTRIBUTING.md[Contributing Guide] for details.
 
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