Add pod condition documentation

[s-vitaliy]

Fixes #218

Scope

Implemented:

• This PR adds the documentation that describes the behavior of the operator that can confuse users. If the pod is deleted and the streaming application does not handle termination gracefully, the job can fail because of incorrect exit code of the container.

Additional changes:

• Improved the streaming job status validation based on the changes of the K8S Job controller behavior described here: Job status.conditions behavior change 1.31 -> 1.32 kubernetes/kubernetes#132144

Checklist

• GitHub issue exists for this change.
• Unit tests added and they pass.
• Line Coverage is at least 80%.
• Review requested on latest commit.

[github-actions]

go-test-coverage report:

Package coverage threshold (70%) satisfied:	PASS
Total coverage threshold (75%) satisfied:	PASS
Total test coverage: 85.3% (405/475)