Add note about migration from auto-discovery

Author: danbarr

docs/toolhive/guides-cli/client-configuration.md

@@ -44,6 +44,20 @@ To view the current status of detected and configured clients, run:
 thv client status
 ```
 
+:::note
+
+ToolHive previously included an "auto-discovery" mode. We removed this mode in
+v0.1.0 to simplify client configuration and ensure consistent control and
+behavior.
+
+If you previously enabled client auto-discovery, ToolHive will explicitly
+register all detected clients the first time you run v0.1.0 and higher.
+
+Going forward, use the `thv client setup` command to manage your client
+configurations.
+
+:::
+
 ## Alternative client registration
 
 If you prefer to register clients manually or in an automated script, use the