[KYUUBI #7676][DOCS] Recommend multi-tenant session config safeguards

docs/security/index.md

@@ -25,6 +25,7 @@ and encryption, etc.
 
 Authentication <authentication>
 Authorization <authorization/index>
+Session Configuration <session_configuration>
 kinit
 hadoop_credentials_manager
 internal_secure_access

docs/security/session_configuration.md

@@ -0,0 +1,40 @@
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+
+# Protect Session Configurations
+
+For a multi-tenant deployment, configure at least one of
+`kyuubi.session.conf.ignore.list` or `kyuubi.session.conf.restrict.list`. Both
+lists are empty by default, so clients can otherwise override sensitive
+session-level configurations during engine bootstrap and connection setup.
+
+One conservative starting point is:
+
+```properties
+kyuubi.session.conf.ignore.list=spark.driver.memory,spark.executor.memory
+kyuubi.session.conf.restrict.list=kyuubi.session.engine.spark.main.resource,kyuubi.engine.share.level,spark.master,spark.submit.deployMode,spark.sql.extensions,spark.sql.optimizer.excludedRules
+```
+
+This example is not comprehensive. Tailor both lists to the deployment. The
+ignore list silently drops matching client values, while the restrict list
+rejects the connection. Some settings are static or consumed during engine
+startup and therefore cannot be changed later. For other settings, configure
+the engine's operation-level restrictions when changes through `SET` statements
+must also be prevented.
+
+See the [session configuration settings](../configuration/settings.md#session)
+for details.