docs: advanced feature note (#24456)

fixes #24430

Author: Erick Friis

docs/scripts/model_feat_table.py

@@ -150,7 +150,13 @@
 
 ## Advanced features
 
-The following table shows all the chat models that support one or more advanced features.
+The following table shows all the chat model classes that support one or more advanced features.
+
+:::info
+While all these LangChain classes support the indicated advanced feature, you may have
+to open the provider-specific documentation to learn which hosted models or backends support
+the feature.
+:::
 
 {table}