Update release docs to cover precise scmReference format

[adamfarley]

Summary

Update release docs to ensure they cover the precise form of the scmReference in the release-openjdk[x]-pipeline jobs, as detailed below.

Details

When testenv had the JDK8 branch set to jdk8u382-b05-aarch32-20230719 and the scmReference for the release job was set to jdk8u382-b05_adopt, the release job did not allow the release to proceed as they did not "match". Example.

Note that the problem isn't the _adopt bit. Changing the scmReference to jdk8u382-b05-aarch32-20230719_adopt worked just fine. Example.