Fix URL syntax in "CI tests with the Checks API" (github#24941)

Author: damiencornu

content/apps/creating-github-apps/guides/creating-ci-tests-with-the-checks-api.md

@@ -98,7 +98,7 @@ Great! Your app has permission to do the tasks you want it to do. Now you can ad
 
 ## Step 1.2. Adding event handling
 
-Now that your app is subscribed to the **Check suite** and **Check run** events, it will start receiving the [`check_suite`](/webhooks-and-events/webhooks/webhook-events-and-payloads#check_suite) and [`check_run`](/webhooks-and-events/webhooks/webhook-events-and-payloads#check_run) webhooks. GitHub sends webhook payloads as `POST` requests. Because you forwarded your Smee webhook payloads to `http://localhost/event_handler:3000`, your server will receive the `POST` request payloads at the `post '/event_handler'` route.
+Now that your app is subscribed to the **Check suite** and **Check run** events, it will start receiving the [`check_suite`](/webhooks-and-events/webhooks/webhook-events-and-payloads#check_suite) and [`check_run`](/webhooks-and-events/webhooks/webhook-events-and-payloads#check_run) webhooks. GitHub sends webhook payloads as `POST` requests. Because you forwarded your Smee webhook payloads to `http://localhost:3000/event_handler`, your server will receive the `POST` request payloads at the `post '/event_handler'` route.
 
 An empty `post '/event_handler'` route is already included in the `template_server.rb` file, which you downloaded in the [prerequisites](#prerequisites) section. The empty route looks like this: