I have to upgrade Kafka from 0.10.0 to 2.0.0 for a production system. Is it a stable release? Also, is there a concept of GA, RC, and M2 for Kafka releases?
Yes Kafka 2.0.0 is a stable release and it can be used in production.
Apache Kafka also uses Release Candidates before releasing new stable versions. For example 2.0.0 went through 3 RCs before reaching GA. (RC0, RC1, RC2).
Apache Kafka however does not use Milestone Releases. A Timed-based release plan was voted by the community and is used to produce regular GA (production ready) releases.