Update README.md with more information on obtaining the credentials w…

…ith required scopes

- the docs were missing the Drive API and required scopes

README.md

@@ -31,7 +31,15 @@ Using the tap this way means you do not have to get any of the following credent
 
 To get your google credentials we recommend reading and following the [OAuth 2.0 Google API Documentation](https://developers.google.com/identity/protocols/oauth2)
 
-The tap calls [Method: spreadsheets.values.get](https://developers.google.com/sheets/api/reference/rest/v4/spreadsheets.values/get?hl=en_GB), and on that page you can see the **required scopes** your credentials need.
+The tap calls the following Google APIs, these need to be enabled in Google Cloud Console
+- [spreadsheets.values.get](https://developers.google.com/sheets/api/reference/rest/v4/spreadsheets.values/get?hl=en_GB)
+- [drive.files.get](https://developers.google.com/drive/api/reference/rest/v3/files/get)
+
+Consent for these scopes needs to be supplied in **required scopes** during OAuth client creation and requested in your authorization flow.
+
+```
+https://www.googleapis.com/auth/spreadsheets.readonly https://www.googleapis.com/auth/drive.readonly
+```
 
 
 **Sheet ID**