Summary:
HeadlessJsTaskConfig parameters can be unclear, so I added one more parameter that was left set by default and the respective comments.
Closes https://github.com/facebook/react-native/pull/16054
Differential Revision: D5881373
Pulled By: hramos
fbshipit-source-id: 3d271f73921417d82e3a2c7a1aaabe92aef7ec69