Propose a pull request for website updates

The final step of building the candidate is to propose a website pull request containing the following changes:

1. update apache/flink-web:_config.yml
   1. update FLINK_VERSION_STABLE and FLINK_VERSION_STABLE_SHORT as required
   2. update version references in quickstarts (q/ directory) as required
   3. (major only) add a new entry to flink_releases for the release binaries and sources
   4. (minor only) update the entry for the previous release in the series in flink_releases
      1. Please pay notice to the ids assigned to the download entries. They should be unique and reflect their corresponding version number.
   5. add a new entry to release_archive.flink
2. add a blog post announcing the release in _posts
3. add a organized release notes page under docs/content/release-notes and docs/content.zh/release-notes (like https://nightlies.apache.org/flink/flink-docs-release-1.15/release-notes/flink-1.15/). The page is based on the non-empty release notes collected from the issues, and only the issues that affect existing users should be included (e.g., instead of new functionality). It should be in a separate PR since it would be merged to the flink project.

Don’t merge the PRs before finalizing the release.

Expectations

• Website pull request proposed to list the release
• (major only) Check docs/config.toml to ensure that
  • the version constants refer to the new version
  • the baseurl does not point to flink-docs-master  but flink-docs-release-X.Y instead