[pom] Add another comment around excluded groups

Author: hazendaz

pom.xml

@@ -132,6 +132,7 @@
 
   <properties>
     <clirr.comparisonVersion>3.4.6</clirr.comparisonVersion>
+    <!-- Add slow test groups here and annotate classes similar to @Tag('groupName'). -->
     <!-- Excluded groups are ran on github ci, to force here, pass -d"excludedGroups=" -->
     <excludedGroups>TestcontainersTests</excludedGroups>
     <maven.compiler.testCompilerArgument>-parameters</maven.compiler.testCompilerArgument>