Add initial release instructions to README

RELEASE.md

@@ -0,0 +1,74 @@
+## Release process
+
+### Release branch
+To release version `X.Y.Z`, first create a and checkout a branch named `release_vX.Y.Z`
+
+```bash
+export VF_VERSION=X.Y.Z
+git checkout main
+git fetch
+git reset --hard origin/main
+git switch -c release_$VF_VERSION
+```
+
+Then update all the package version strings to `X.Y.Z` using the `automation/bump_version.py` script
+
+```bash
+python automation/bump_version.py $VF_VERSION
+```
+
+Open a pull request to merge this branch into `main`.  This will start the continuous integration jobs on GitHub Actions. These jobs will test VegaFusion and build packages for publication.
+
+### Publish Python packages
+To publish the `vegafusion-python-embed` packages to PyPI, first download and unzip the `vegafusion-python-embed-wheels` artifacts from GitHub Actions. Then `cd` into the directory of `*.whl` and `*.tar.gz` files and upload the packages to PyPI using [twine](https://pypi.org/project/twine/).
+
+```bash
+cd vegafusion-python-embed-wheels
+twine upload *
+```
+
+To publish the `vegafusion` packages, download and unzip the `vegafusion-wheel` artifacts. Then upload with twine.
+
+```bash
+cd vegafusion-wheel
+twine upload *
+```
+
+To publish the `vegafusion-jupyter` packages, download and unzip the `vegafusion-jupyter-packages` artifacts. Then upload with twine.
+
+```bash
+cd vegafusion-jupyter-packages
+twine upload *
+```
+
+### Publish NPM packages
+First, download and unzip the `vegafusion-wasm-packages` artifact. Then publish the `vegafusion-wasm-X.Y.Z.tgz` package to NPM.  If this is a release candidate, include the `--pre` flag to `npm publish`.
+
+```bash
+cd vegafusion-wasm-packages
+npm publish vegafusion-wasm-$VF_VERSION.tgz
+```
+
+Next, change the version of `vegafusion-wasm` in `javascript/vegafusion-embed/package.json` from `"../../vegafusion-wasm/pkg"` to `"~X.Y.Z"`
+
+Then update `package.lock`, and build package, then publish to NPM (include the `--pre` flag to `npm publish` if this is a release candidate)
+```bash
+cd javascript/vegafusion-embed/
+npm install
+npm run build 
+npm publish
+```
+
+Next, change the version of `vegafusion-wasm` and `vegafusion-embed` in `python/vegafusion-jupyter/package.json` from local paths to `"~X.Y.Z"`
+
+Then build and publish the packages (include the `--pre` flag if this is a release candidate)
+
+```bash
+cd python/vegafusion-jupyter/
+npm install
+npm run build:prod
+npm publish
+```
+
+### Publish Rust crates
+TBD. There are still some git-based dependencies (e.g. sql-gen) that prevent publication to crates.io