[test] A documentation on how to run the werft job

Author: geropl

test/README.md

@@ -15,4 +15,17 @@ Such tests are for example:
 - instrumentation: agents that are compiled before/during the test, uploaded to a pod and executed there.
                    They communicate with the test using net/rpc.
 - API access: to all internal APIs, including ws-manager, ws-daemon, image-builder, registry-facade, server
-- DB access to the Gitpod DB
+- DB access to the Gitpod DB
+
+## Run
+
+There is a [werft job](../.werft/run-integration-tests.yaml) that runs the integration tests against `core-dev` preview environments.
+
+ > For tests that require an existing user the framework tries to automatically select one from the DB.
+ > - On preview envs make sure to create one before running tests against it!
+ > - If it's important to use a certain user (with fixed settings, for example) pass the additional `username` parameter.
+
+Example command:
+```
+werft job run github -j .werft/run-integration-tests.yaml -a namespace=staging-gpl-2658-int-tests -a version=gpl-2658-int-tests.57 -f
+```