RE: #1421, Add documentation about creating a GitHub release after creating a tag

Author: catarak

developer_docs/release.md

@@ -19,6 +19,13 @@ This project release guide is based on
 7. `$ git push && git push --tags`
 8. `$ git checkout develop`
 9. `$ git merge --no-ff release-<newversion>`
+10. Create a release on GitHub. You can do this in one of two ways:
+    1.  (Preferred) Use the [`hub` command line tool](https://hub.github.com/). You can automate adding all commit messages since the last release with the following command:
+        ```sh
+        $ hub release create -d -m "<newversion>" -m "$(git log `git describe --tags --abbrev=0 HEAD^`..HEAD --oneline)" <newversion>`
+        ```
+        Note that this creates a draft release, which you can then edit on GitHub. This allows you to create release notes from the list of commit messages, but then edit these notes as you wish.
+    2.  [Draft a new release on Github](https://github.com/processing/p5.js-web-editor/releases/new).
 
 Travis CI will automatically deploy the release to production, as well as push a production tagged Docker image to DockerHub.