Error message when missing GitHub token is difficult to understand for new users

[danbasszeti]

When the GitHub token isn't passed, this error comes through. The BenchmarkDotnet example doesnt have the github token on it, so when i copy pasted it I didn't realise it was necessary. I can see in the code of this repo where this error is being sent back and would be happy to put in my own PR to amend it if wanted?