Implement Versioning SNAPSHOT Tags for released container images

[hamidonos]

Situation

Currently, we don't have a structured versioning system in place for released container imges. Tags are without common distinctions between early-stage features, ongoing development, and (pre-)release versions. This lack of versioning tags such as ALPHA, SNAPSHOT, and RC makes it harder for consumers to identify what state a artifact is in.

Wanted:

To improve our release process and ensure better control over software stability and feature development, we should adopt a versioning strategy using tags like ALPHA, SNAPSHOT, and RC (Release Candidate).

ALPHA: For early development phases, allowing us to test incomplete features and gather feedback.

SNAPSHOT: For continuous integration builds that are not production-ready, ensuring quick iteration without affecting stable releases.

RC: For stable, pre-release versions that are nearly ready for production, helping with final testing and bug fixes.

Solution

For now we should use -SNAPSHOT to mark testing & development artifacts in our ghcr.io

Example Tag (SecHub server): 1.10.0_alpine_sven_20240918-SNAPSHOT

-> extend documentation accordingly

[sven-dmlr]

Updated description (limit to container images)