Propose and document the `get out of alpha` process

[pPrecel]

Description:

All sub-commands under the alpha command should be "released" if all quality requirements are met. We should propose and document which requirements we expect to fully support command and not keep it anymore in the alpha phase.

Requirements:

• [ ] should be located in the docs/contributor
• [ ] should describe how to decide when a command is ready to get out of the alpha state

Hints:

Requirements should be easy to measure to not operate on subjective sentences. Example:

• happy-path integration test
• unit tests
• accepted API by someone (for example team)