message: Add extra description for Subscribe API
diff: },
  "/subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/microsoft.insights/actionGroups/{actionGroupName}/subscribe": {
  "post": {
  - "description": "Enable a receiver in an action group. This changes the receiver's status from Disabled to Enabled.",
  + "description": "Enable a receiver in an action group. This changes the receiver's status from Disabled to Enabled. This operation is only supported for Email or SMS receivers.",
  "operationId": "ActionGroups_EnableReceiver",
  "x-ms-examples": {
  "Enable the receiver": {
  