docs: add release process to Development.md

DEVELOPMENT.md

@@ -15,6 +15,10 @@
     - [Adding examples](#adding-examples)
   - [Creating a Pull Request](#creating-a-pull-request)
   - [Working with Jupyter Notebooks](#working-with-jupyter-notebooks)
+  - [Releasing a New Version](#releasing-a-new-version)
+    - [Prerequisites](#prerequisites-1)
+    - [Versioning](#versioning)
+    - [Release Steps](#release-steps)
 
 ## Introduction
 
@@ -125,3 +129,64 @@ This library is packaged with examples that can be downloaded via the doc websit
   make jupyter
   ```
 
+## Releasing a New Version
+
+### Prerequisites
+
+1. **PyPI maintainer access**: You must be added as a maintainer on the [biolearn PyPI project](https://pypi.org/project/biolearn/). Contact an existing maintainer to be added.
+2. **PyPI API token**: Generate a project-scoped API token at [pypi.org/manage/account/token](https://pypi.org/manage/account/token/). Scope it to the `biolearn` project only.
+3. **Hatch**: Install the build/publish tool globally:
+   ```bash
+   pipx install hatch
+   ```
+
+### Versioning
+
+This project uses [Semantic Versioning](https://semver.org/) (`MAJOR.MINOR.PATCH`) with the `hatch-vcs` plugin, which derives the package version from git tags automatically.
+
+Biolearn is currently pre-1.0, meaning the library is not yet considered stable. In the `0.x` range:
+
+- **PATCH** (e.g., 0.9.0 → 0.9.1): Bug fixes and small additions
+- **MINOR** (e.g., 0.9.1 → 0.10.0): New features, may include breaking changes
+- **MAJOR** (e.g., 0.10.0 → 1.0.0): Major release, stable library with comprehensive clock and feature coverage
+
+Tags use the `v` prefix (e.g., `v0.9.0`). You **must** tag before building — otherwise hatch produces a dev version.
+
+### Release Steps
+
+1. **Ensure master is clean and tests pass**
+   ```bash
+   git checkout master
+   git pull origin master
+   make test
+   ```
+
+2. **Tag the release**
+   ```bash
+   git tag v0.X.Y
+   git push origin v0.X.Y
+   ```
+
+3. **Build**
+   ```bash
+   hatch build -c
+   ```
+   Verify the filenames in `dist/` show the correct version with no `dev` suffix.
+
+4. **Publish to PyPI**
+   ```bash
+   export HATCH_INDEX_USER=__token__
+   export HATCH_INDEX_AUTH=<your-api-token>
+   hatch publish
+   ```
+
+5. **Build and publish documentation**
+   ```bash
+   source .venv/bin/activate
+   cd doc
+   make html
+   ```
+   Copy the contents of `doc/_build/html/` into the [bio-learn.github.io](https://github.com/bio-learn/bio-learn.github.io) repo and push.
+
+**Note:** The Makefile has a `publish` target (`make publish`) but it references `.venv/bin/hatch` which may not be available. Use a globally installed `hatch` as described above.
+