Update maintainer notes

Author: fstab

MAINTAINER_NOTES.md

@@ -7,3 +7,14 @@ Use the [Versions Maven Plugin](https://www.mojohaus.org/versions-maven-plugin/i
 ```
 ./mvnw versions:use-latest-releases
 ```
+
+## Release
+
+```
+./mvnw release:prepare -DreleaseVersion=0.16.0 -DdevelopmentVersion=0.16.1-SNAPSHOT
+./mvnw release:perform -DreleaseVersion=0.16.0 -DdevelopmentVersion=0.16.1-SNAPSHOT
+```
+
+`release:prepare` does Github tags and commits, while `release:perform` signs the artifacts and uploads them to the staging repositoring on [https://oss.sonatype.org](https://oss.sonatype.org).
+
+After that, manually verify the uploaded artifacts on [https://oss.sonatype.org/#stagingRepositories](https://oss.sonatype.org/#stagingRepositories), click `Close` to trigger Sonatype's verification, and then `Release`.