Update README.md example snippet

[FredKSchott]

PR Checklist:

• I have run npm test locally and all tests are passing.
• I have added/updated tests for any new behavior.
  
• If this is a significant change, an issue has already been created where the problem / solution was discussed: N/A
  

PR Description

Small change, but it's easy to copy and paste this example, change the URL, and get a completely silent and confusing callback. We saw this in #2557.