Add release cycle

[cristiklein]

⚠️ IMPORTANT ⚠️: This is a public repository. Make sure to not disclose:

• [x] personal data beyond what is necessary for interacting with this Pull Request;
• [x] business confidential information, such as customer names.

Quality gates:

• [x] I'm aware of the Contributor Guide and did my best to follow the guidelines.
• [x] I'm aware of the Glossary and did my best to use those terms.

We decided to publish our release cycles for better internal and external alignment.

Note to reviewers: The release cycle of AMSes is TBD.