docs: Correct URL (#1204)
docs: Correct URL (#1204)

Current hyperlink takes you to a non-existent page. 
Before Change : https://github.com/octokit/webhooks.js/blob/master/lib/webhook-names.json
After Change : https://github.com/octokit/webhooks.js/
probot/probot,probot/probot,bkeepers/PRobot,probot/probot,bkeepers/PRobot