Update description of runId to infer customer to use new GUID for create run (#29447)

* Update description of runId to infer customer to use new GUID for create run

* Refine description

Author: mschaofan

specification/synapse/data-plane/Microsoft.Synapse/preview/2022-03-01-preview/runNotebook.json

@@ -534,7 +534,7 @@
       "maxLength": 100,
       "required": true,
       "type": "string",
-      "description": "Notebook run id.",
+      "description": "Notebook run id. For Create Run, you can generate a new GUID and use it here. For other actions, this is the same ID used in Create Run.",
       "x-ms-parameter-location": "method"
     },
     "Endpoint": {