update spark 4 notes

Author: razvan

docs/modules/spark-k8s/partials/supported-versions.adoc

@@ -7,8 +7,7 @@
 - 3.5.6 (Hadoop 3.3.4, Scala 2.12, Python 3.11, Java 17) (Deprecated)
 - 3.5.7 (Hadoop 3.3.4, Scala 2.12, Python 3.11, Java 17) (LTS)
 
-Some reasons why Spark 4 is considered experimental (as of August 2025):
+Some reasons why Spark 4 is considered experimental (as of September 2025):
 
 - Missing HBase compatibility (See: https://github.com/apache/hbase-connectors/pull/130)
-- Missing Iceberg compatibility (See: https://github.com/apache/iceberg/issues/13358)
 - Executors fail to load logging libs (maybe related: https://issues.apache.org/jira/browse/SPARK-52585)