docs: Add example for pipeline_settings

Add an example for the pipeline_settings setting to demonstrate what format it expects.

Co-authored-by: Jan Macku <jamacku@redhat.com>
Co-authored-by: Miroslav Vadkerti <mvadkert@redhat.com>

README.md

@@ -68,7 +68,7 @@ See [Testing Farm onboarding guide](https://docs.testing-farm.io/Testing%20Farm/
 | `debug` | Print debug logs when working with testing farm | true |
 | `update_pull_request_status` | Action will update pull request status. | false |
 | `environment_settings` | Pass custom settings to the test environment. | empty |
-| `pipeline_settings` | Pass specific settings for the testing farm pipeline. For details see settings/pipeline in [Request new test](https://api.testing-farm.io/redoc#operation/request_a_new_test_v0_1_requests_post) | empty |
+| `pipeline_settings` | Pass specific settings for the testing farm pipeline. For example, `'{ "type": "tmt-multihost" }'`. For details, see `settings.pipeline` field in [Request new test](https://api.testing-farm.io/redoc#operation/request_a_new_test_v0_1_requests_post). | empty |
 | `create_github_summary` | Create summary of the Testing Farm as GiHub Action job. Possible options: "false", "true", "key=value" | true |
 | `timeout` | Timeout for the Testing Farm job in minutes. | 480 |