Add docs for kubectl subresource support

content/en/docs/reference/kubectl/conventions.md

@@ -19,6 +19,16 @@ For a stable output in a script:
 * Fully-qualify the version. For example, `jobs.v1.batch/myjob`. This will ensure that kubectl does not use its default version that can change over time.
 * Don't rely on context, preferences, or other implicit states.
 
+## Subresources
+
+* You can use the `--subresource` alpha flag for kubectl commands like `get`, `patch`,
+`edit` and `replace` to fetch and update subresources for all resources that
+support them. Currently, only the `status` and `scale` subresources are supported.
+* The API contract against a subresource is identical to a full resource. While updating the
+`status` subresource to a new value, keep in mind that the subresource could be potentially
+reconciled by a controller to a different value.
+
+
 ## Best Practices
 
 ### `kubectl run`