feat(k6-operator): add troubleshooting to image with extension to 1.2.x

Author: yorugac

docs/sources/k6/v1.2.x/set-up/set-up-distributed-k6/troubleshooting.md

@@ -45,9 +45,9 @@ The k6 runners fail to start, and in the k6 Operator logs, you see the `unable t
 
 1. Your Kubernetes setup includes some tool that is implicitly adding symbols to the log output of Pods. You can verify this case by checking the logs of the initializer Pod: they should contain valid JSON, generated by k6. Currently, to fix this, the tool adding symbols must be switched off for the k6 Operator workloads.
 
-2. Multi-file script includes many files which all must be fully accessible from the runner Pod. You can verify this case by checking the logs of the initializer Pod: there will be an error about some file not being found. To fix this, refer to [Multi-file tests](https://grafana.com/docs/k6/latest/set-up/set-up-distributed-k6/usage/executing-k6-scripts-with-testrun-crd/#multi-file-tests) on how to configure multi-file tests in `TestRun`.
+1. Multi-file script includes many files which all must be fully accessible from the runner Pod. You can verify this case by checking the logs of the initializer Pod: there will be an error about some file not being found. To fix this, refer to [Multi-file tests](https://grafana.com/docs/k6/latest/set-up/set-up-distributed-k6/usage/executing-k6-scripts-with-testrun-crd/#multi-file-tests) on how to configure multi-file tests in `TestRun`.
 
-3. There are problems with environment variables or with importing an extension. Following the steps found in [testing locally](#test-your-script-locally) can help debug this issue. One additional command that you can use to help diagnose issues with your script is the following:
+1. There are problems with environment variables or with importing an extension. Following the steps found in [testing locally](#test-your-script-locally) and in [troubleshooting extensions](https://grafana.com/docs/k6/latest/set-up/set-up-distributed-k6/usage/extensions#troubleshooting) can help debug this issue. One additional command that you can use to help diagnose issues with your script is the following:
 
 ```bash
 k6 inspect --execution-requirements script.js

docs/sources/k6/v1.2.x/set-up/set-up-distributed-k6/usage/extensions.md

@@ -59,3 +59,12 @@ spec:
 ```
 
 Note that this examples overrides the default image with `k6-extended:latest`, and it includes environment variables that are required by the `xk6-output-influxdb` extension.
+
+## Troubleshooting
+
+If a `TestRun` with a custom image doesn't start the test and the k6 Operator [logs an error about the initializer](https://grafana.com/docs/k6/latest/set-up/set-up-distributed-k6/troubleshooting/#an-error-on-reading-output-of-the-initializer-pod), run the following command:
+
+```sh
+docker run --entrypoint sh k6-extended:local -c "ls -l && k6 version"
+
+This command should execute without an error. If there's an error, resolve it by making sure that the `Dockerfile` is correctly configured. Use the sample above as a reference.