reference/kubectl: Update docs for moving feaature to beta

Signed-off-by: Madhav Jivrajani <madhav.jiv@gmail.com>

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

@@ -22,9 +22,11 @@ For a stable output in a script:
 
 ## Subresources
 
-* You can use the `--subresource` alpha flag for kubectl commands like `get`, `patch`,
+* You can use the `--subresource` beta 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.
+  * For `kubectl edit`, the `scale` subresource is not supported. If you use  `--subresource` with
+    `kubectl edit` and specify `scale` as the subresource, the command will error out.
 * 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.