docs(pluginChartTest) minor improvements (#614)

docs/user-guides/plugin/plugin-tests.md

@@ -150,6 +150,7 @@ Before submitting a pull request:
 - Test your Plugin thoroughly using `helm test <release-name>` and confirm that all tests pass against a test Kubernetes cluster.
 - Include a brief description of the tests in your pull request.
 - Make sure that your Plugin's Chart Directory and the Plugin's Upstream Chart Repository are added to this [greenhouse-extensions helm test config file](https://github.com/cloudoperators/greenhouse-extensions/blob/main/.github/configs/helm-test.yaml). This will ensure that your Plugin's tests are automatically run in the GitHub Actions workflow when you submit a pull request for this Plugin.
+- Note that the [dependencies](https://helm.sh/docs/helm/helm_dependency/) of your Plugin's helm chart might also have their own tests. If so, ensure that the tests of the dependencies are also passing.
 
 **Important Notes**