Merge pull request travis-ci#1288 from nh2/patch-1

running-build-in-debug-mode.md: Explain what kind of ID is needed and…

Author: MariadeAnton

user/running-build-in-debug-mode.md

@@ -43,8 +43,14 @@ $ curl -s -X POST \
   https://api.travis-ci.org/job/${id}/debug
 ```
 
+(Note the literal word `token` must be present before the actual authorization token.)
+
 For private repositories, the API endpoint is `https://api.travis-ci.com/job/${id}/debug`.
 
+#### Finding the job ID
+
+The `${id}` is a job ID, not a build ID. For example, the ID `248927956` in the URL [`https://travis-ci.org/travis-ci/docs-travis-ci-com/builds/248927956`](https://travis-ci.org/travis-ci/docs-travis-ci-com/builds/248927956) is a build ID. To obtain the corresponding job ID, click the _View config_ button on that page, and the URL will change into [`https://travis-ci.org/travis-ci/docs-travis-ci-com/jobs/248927957/config`](https://travis-ci.org/travis-ci/docs-travis-ci-com/jobs/248927957/config), showing the job ID `248927957`. Alternatively, you can obtain job IDs corresponding to a build ID [via the API](https://docs.travis-ci.com/api/#builds).
+
 #### Echoing debug session's output to the logs
 
 To show any command input and output you see while connected to the VM running in the debug