You will need to have the staging repository configured on your system, e.g in a staging profile as I have in the example above. Also, make sure to delete the starter from your local repository if you have built it yourself, so you are sure you are testing the right artifact.
  <profiles>
     <profile>
      <id>staging</id>
      <activation>
        <activeByDefault>false</activeByDefault>
      </activation>
      <repositories>
        <repository>
          <id>jakarta-nexus-staging</id>
          <name>Sonatype Nexus Staging</name>
          <url>
https://jakarta.oss.sonatype.org/content/groups/staging/</url>
          <releases>
            <enabled>true</enabled>
          </releases>
          <snapshots>
            <enabled>false</enabled>
          </snapshots>
        </repository>
      </repositories>
     </profile>
   </profiles>
I have updated the README file in the release branch with the correct groupId and version. This will be merged into master when the release is done. So there is no need to update the README file in the master branch before that.