Add note about slow Sonatype updates

Author: pglombardo

RELEASE.md

@@ -5,7 +5,9 @@
 
 ## Notes
 
-Java client releases are done through a Github Action in [publish.yml](https://github.com/hivemq/hivemq-mqtt-client/blob/master/.github/workflows/publish.yml) that is triggered by publishing a new release.
-
-The publish action publishes the Java client library to Maven using the version in `gradle.properties`.
+1. Java client releases are done through a Github Action in [publish.yml](https://github.com/hivemq/hivemq-mqtt-client/blob/master/.github/workflows/publish.yml) that is triggered by publishing a new release.
+2. The publish action publishes the Java client library to Maven using the version in `gradle.properties`.
+3. The Maven/Sonatype UIs take up to 24 hours to show the new version (facepalm).
+4. Check here for an immediate view: https://repo1.maven.org/maven2/com/hivemq/hivemq-mqtt-client/
+5. The Sonatype page for reference: https://central.sonatype.com/artifact/com.hivemq/hivemq-mqtt-client