chore: tidy the legacy content out of .github

CONTRIBUTING.md

@@ -1,37 +1,62 @@
 # Contributing to Radius Red
 
-We welcome contributions to Radius Red's open source repositories.
+Radius Red Ltd. is a UK-based, agentic engineering company. This GitHub
+organisation hosts the open-source tools and shared automation we maintain in
+public; the [organisation profile](profile/README.md) says how we work.
 
-This repository (`.github`) holds shared GitHub Actions workflows, organisation
-profile content, and cross-repo documentation. For project-specific guidance,
-refer to the `CONTRIBUTING.md` in each repository:
+## What this repository holds
 
-- [`tradedesk`](https://github.com/radiusred/tradedesk)
-- [`tradedesk-dukascopy`](https://github.com/radiusred/tradedesk-dukascopy)
-- [`tradedesk-miner`](https://github.com/radiusred/tradedesk-miner)
+`.github` is the organisation's shared-asset repository. It holds only what
+other repositories consume:
 
-## Getting Started
+- `.github/workflows/reusable-release.yml` and
+  `.github/workflows/reusable-finalize-release.yml` — the reusable release
+  workflows, called by
+  [`tradedesk`](https://github.com/radiusred/tradedesk) and
+  [`tradedesk-dukascopy`](https://github.com/radiusred/tradedesk-dukascopy)
+  from their `prepare-release` and `finalize-release` workflows.
+- `.github/actions/calculate_version` — the version-calculation action the
+  release workflow runs.
+- `profile/` — the organisation profile shown at
+  [github.com/radiusred](https://github.com/radiusred).
 
-1. Fork the repository and create a feature branch from `main`.
-2. Install dependencies and run tests locally if applicable.
+Beyond those, the repository carries only its own housekeeping: this file,
+`.gitignore`, and `.codecrew.yml`, which points CodeCrew coordination for this
+repository at the company hub. Each project's documentation lives with the
+project.
 
-## Standards
+## Contributing to a project
 
-- Keep changes small, well-scoped, and documented in PR descriptions.
-- Open PRs against `main`; rebase rather than merge commits.
-- Provide a brief rationale and expected impact in the PR description.
-- Include tests or updates to tests if the change affects behaviour.
-- Do not include secrets or internal data in public PRs.
+Contributions are accepted per project. Each project repository carries its
+own `README.md` and, where the project takes contributions, a
+`CONTRIBUTING.md`; follow those. The current list is at
+[github.com/orgs/radiusred/repositories](https://github.com/orgs/radiusred/repositories).
+(This repository is not a project: `profile/README.md` is the organisation
+profile GitHub shows on the org page, not a repository README, and this file
+is its contributing guide.)
 
-## Documentation
+If you are unsure whether a change is wanted, open an issue in the repository
+concerned describing the goal before writing the code.
 
-- Update public docs with exact references to shipped code.
-- Reference merged PRs or docs for traceability.
+## Changing this repository
 
-## Reporting Issues
+`main` is protected: changes arrive by pull request, history is linear (rebase
+only, no merge commits), and commit messages follow
+[Conventional Commits](https://www.conventionalcommits.org/).
 
-If unsure about scope or approach, open an issue describing the goal and request
-guidance before implementing.
+- Callers reference the reusable workflows and the action at `@main`, so a
+  merge here is live for every caller at once. Say in the PR which callers you
+  checked, and keep workflow inputs, secrets and outputs backward compatible
+  or land the callers' change alongside.
+- Keep the profile accurate; it is what a visitor to the organisation sees
+  first.
+- Never include secrets or internal data in a public PR.
+
+## Security
+
+To report a vulnerability in any Radius Red project, email
+[[email protected]](mailto:[email protected]) rather than opening
+a public issue.
 
 ---
 
@@ -40,4 +65,4 @@ guidance before implementing.
 Licensed under the Apache License, Version 2.0.
 See: https://www.apache.org/licenses/LICENSE-2.0
 
-Copyright 2026 [Radius Red Ltd.](https://github.com/radiusred)
+Copyright 2026 [Radius Red Ltd.](https://www.radiusred.uk)