[smaranjit]

What does this change?

Bumps the version to 0.2.1 and moves the [Unreleased] changelog entry under [0.2.1].

This release ships #22 to users: the About dialog now has a "Find it useful? Star it on GitHub" line. The README and user-guide changes from #22 are already live.

It's a patch release because nothing else changed.

Checklist

• cargo fmt --all -- --check passes
• cargo clippy --all-targets -- -D warnings passes
• cargo test --all-targets passes
• cargo build --release succeeds
• Tested manually against a Firebase project (a development one), as part of Ask for a GitHub star in the README, guide and About dialog #22
• CHANGELOG.md updated, here by cutting [Unreleased] into [0.2.1]

Notes for the reviewer

After merge, v0.2.1 is tagged on the merged commit, and release.yml builds and publishes the release.