Add prerequisites to maintainers.md

docs/development/maintainers.md

@@ -111,17 +111,24 @@ Cherry pick the corresponding documentation commits to the `stable` branch. Use
 
 ### Upgrading pyodide to a new version of CPython
 
+Prerequisites -- The desired version of CPython must be available at:
+
+1. The `specific release` section of https://www.python.org/downloads
+2. https://hub.docker.com/_/python
+3. https://github.com/actions/python-versions/releases
+
 For example: `v3.11.1` -> `v3.11.2`
 
 1. Download the **Gzipped source tarball** at https://www.python.org/downloads/release/python-3112 into `downloads/`
 2. `shasum -a 256 downloads/Python-3.11.2.tgz > cpython/checksums`
+   - Ensure the path in `cpython/checksums` starts with `downloads/Python-`
 3. `git grep --name-only "3.11.1" ` # All these files will need to be updated.
 4. After updating the Python version in `Dockerfile`, create a new Docker image.
    - A maintainer must click `Run workflow` on https://github.com/pyodide/pyodide/actions/workflows/docker_image.yml
 5. That workflow will build and upload a new Docker image to https://hub.docker.com/r/pyodide/pyodide-env/tags
-6. Modify the image name in `.circleci/config.yml` to match the image tag on Docker Hub.
+6. In `.circleci/config.yml` modify the image name to match the image tag on Docker Hub.
    - `image: pyodide/pyodide-env:20230301-chrome109-firefox109-py311`
-7. Modify the `PYODIDE_IMAGE_TAG` in `run_docker` to match the image tag on Docker Hub.
+7. In `run_docker` modify the `PYODIDE_IMAGE_TAG` to match the image tag on Docker Hub.
    - `PYODIDE_IMAGE_TAG="20230301-chrome109-firefox109-py311"`
 8. Rebase any patches which do not apply cleanly.
-9. Create a pull request and fix any failing tests. This may be complicated for major releases of CPython.
+9. Create a pull request and fix any failing tests. This may be complicated for non-micro releases of CPython.