Releasing

The following steps publish the plugin to both Maven Central and Gradle Plugin Portal:

Change the version in top-level gradle.properties to a non-SNAPSHOT version.
Update the CHANGELOG.md for the impending release.
Update the README.md with the new version.
git commit -am "Prepare for release X.Y.Z." (where X.Y.Z is the new version).
./gradlew publishAndReleaseToMavenCentral
Visit Sonatype Nexus to verify the release has been completed.
git tag -a X.Y.X -m "X.Y.Z" (where X.Y.Z is the new version)
Update the top-level gradle.properties to the next SNAPSHOT version.
git commit -am "Prepare next development version."
git push && git push --tags

If step 5 or 6 fails, drop the Sonatype repo, fix the problem, commit, and start again at step 5.