[Update] GET account/maintenance (#311)

Author: sagesyr

openapi.yaml

@@ -1008,6 +1008,12 @@ paths:
 
 
         Currently, Linodes are the only entities available for viewing.
+
+
+        **Beta**: This endpoint is in beta. Please make sure to prepend all requests with
+        `/v4beta` instead of `/v4`, and be aware that this endpoint may receive breaking
+        updates in the future. This notice will be removed when this endpoint is out of
+        beta.
       operationId: getMaintenance
       x-linode-cli-action: maintenance-list
       security: