This isn't necessary. This constant *isn't* documentation. It's used by the metadata launcher to strip options that aren't strictly instance metadata. `'wait'` should not be passed in from the role file. See [this block](https://github.com/airbnb/stemcell/blob/72489eec4f4a237e5968734e01c44815521fd911/lib/stemcell/metadata_launcher.rb#L102-L105).