document the different types of releases.
document the different types of releases.

PiperOrigin-RevId: 434806996
Change-Id: I4fdf50ff447321b39434fc697da66bda854d33ea

GoogleCloudPlatform/appengine-java-standard,GoogleCloudPlatform/appengine-java-standard,GoogleCloudPlatform/appengine-java-standard,GoogleCloudPlatform/appengine-java-standard