Document that reserved namespaces org.docker.*, io.docker.*, and
org.dockerproject.* in engine labels are now deprecated.
@@ -19,6 +19,16 @@ The following list of features are deprecated in Engine.
To learn more about Docker Engine's deprecation policy,
see [Feature Deprecation Policy](https://docs.docker.com/engine/#feature-deprecation-policy).
+### Reserved namespaces in engine labels
+
+**Deprecated in Release: v18.06.0**
+
+The namespaces `com.docker.*`, `io.docker.*`, and `org.dockerproject.*` in engine labels
+were always documented to be reserved, but there was never any enforcement.
+
+Usage of these namespaces will now cause a warning in the engine logs to discourage their
+use, and will error instead in 18.12 and above.
+
### Asynchronous `service create` and `service update`
**Deprecated In Release: v17.05.0**
