Update release instructions with our actual Changelog format
1. Create a PR "Preparing for release X.Y.Z" against master branch
* Update VERSION to `X.Y.Z`
- * Alter CHANGELOG.md from `[Unreleased]` to `<X.Y.Z> (YYYY-MM-DD)`
+ * Alter CHANGELOG.md from `[Unreleased]` to `[X.Y.Z] YYYY-MM-DD`
2. Create a release "Release X.Y.Z" on Github
* Create Tag `vX.Y.Z`
