Release v0.2.0

[e-backmark-ericsson]

• Make sure all issues are resolved: https://github.com/cdevents/spec/milestone/2
• Switch all versions from 0.2.0-draft to 0.2.0 Prepare for release v0.2.0 #120
• Switch all event versions from version-draft to version Prepare for release v0.2.0 #120
• Remove mentions of draft / work-in-progress content Prepare for release v0.2.0 #120
• Update the README to mention 0.2.0 as latest release Prepare for release v0.2.0 #120
• Tag spec and create branch for patch releases
• Produce release notes through GitHub
• Update cdevents.dev as needed Prepare for v0.2 cdevents.dev#34
• Prepare a release announcement for v0.2 (see Release announcement #47 for reference)
• Announce release on slack and mailing list
• Move main in the spec repo to the new -draft release