Change Iaad7a3b50e14d5f0ef25c52bcc070b7601d46a8f removed the release
notes building but this is not mentioned in the commit message at all,
so looks like an accident - re-add them.
The release notes are currently only updated when a stable/rocky change
merges but not for master changes since stable/rocky has a release-notes
job but master not.
Change-Id: I3c2c67b652fa2ef824f29189bf815965c8a804ab