clarify it is a filename

example.config.json

@@ -20,10 +20,10 @@
             "bot_token": "optional, but allows access to more content such as large videos, talk to @botfather"
         },
         "google_sheets": {
-            "service_account": "normally service_account.json, see https://gspread.readthedocs.io/en/latest/oauth2.html#for-bots-using-service-account"
+            "service_account": "local filename: normally service_account.json, see https://gspread.readthedocs.io/en/latest/oauth2.html#for-bots-using-service-account"
         },
         "google_drive": { // for storage=gd
-            "service_account": "can be the same or different file from google_sheets defaults to service_account.json",
+            "service_account": "local filename: can be the same or different file from google_sheets.service_account defaults to service_account.json",
             "root_folder_id": "copy XXXX from https://drive.google.com/drive/folders/XXXX"
         },
         "local":{ // for storage=local