There is a script `release.sh` which does the following, but if you need to do
a release manually, here are the steps:

- `git checkout -b release-v0.x.x`
- Update `CHANGELOG.md`
- `npm version 0.x.x`
- Merge `release-v0.x.x` onto `master`.
- Push `master`.
- Push the tag: `git push --tags`
- `npm publish`
- Generate documentation: `npm run gendoc` (this outputs HTML to `.jsdoc`)
- Copy the documentation from `.jsdoc` to the `gh-pages` branch and update `index.html`
- Merge `master` onto `develop`.
- Push `develop`.