Image update automation semver improvements

[iapain]

Consider following workflow:

• Create a tag v1.0.0 and push
• CI builds an image and add it to a registry server.
• GitRepostory scans for semver: >=1.0.0 <2.0.0
• ImageUpdateAutomation updates image in yaml manifest and pushes it to git.

So far so good. Since our GitRepository scans for >=1.0.0 <2.0.0 commit from ImageUpdateAutomation is obviously not on that tag, hence deployment will be never updated. If it's a correct behavior then we should definitely improve https://fluxcd.io/docs/guides/image-update/ documentation. Otherwise, We should add an option to create a tag in ImageUpdateAutomation.

[squaremo]

The version of your image source is not in general related to the version of your config. I think you want to follow a branch, rather than a semver, in your GitRepository.

If your intent is to line your application image versions with deployed config versions in the same git repository, it's a bit tricky, since the tag has already been created when the automation runs:

• commit application code change
• tag v1.0.1 for image build
• image:v1.0.1 pushed to registry
• flux automation makes update to config
• tag the config as .. ?