Add note about triage auth token (#8356)

Author: helin24

tool/triage/README.md

@@ -1,10 +1,10 @@
-
 # Triage Reporting Utilities
 
-To get generate a report on untriaged issues, run:
+To generate a report on untriaged issues, run:
 
 ```
-dart bin/triage.dart
+dart bin/triage.dart <optional auth token>
 ```
 
-(Optionally pass an auth token as an argument.)
+The optional auth token allows running this job many
+times. [Instructions to generate](https://docs.github.com/en/authentication/keeping-your-account-and-data-secure/managing-your-personal-access-tokens#creating-a-fine-grained-personal-access-token)