protect ourselves from the freedom of changing the internal config

Author: HeartSaVioR

sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala

@@ -2627,8 +2627,11 @@ object SQLConf {
 
   val STATEFUL_SHUFFLE_PARTITIONS_INTERNAL =
     buildConf("spark.sql.streaming.internal.stateStore.partitions")
-      .doc("The default number of partitions to use when shuffling data for stateful operations. " +
-        "If not specified, this config picks up the value of `spark.sql.shuffle.partitions`." +
+      .doc("WARN: This is used internally and not intended to be a user facing one. This config " +
+        "can be removed without support of compatibility in any time. " +
+        "DO NOT USE THIS CONFIG DIRECTLY AND USE THE CONFIG `spark.sql.shuffle.partitions`. " +
+        "The default number of partitions to use when shuffling data for stateful operations. " +
+        "If not specified, this config picks up the value of `spark.sql.shuffle.partitions`. " +
         "Note: For structured streaming, this configuration cannot be changed between query " +
         "restarts from the same checkpoint location.")
       .internal()