Setup a second watch and verify setup guide

[c-pius]

Description

Test the setup of a second watch on an SKR resource and verify that the setup guide is usable.

Reasons

Frogs now want to start adopting runtime-watcher. We should be sure that the onboarding guide is up to date and complete.

AC

• second watch on a resource, e.g. a ConfigMap, created
• events regarding that resource reach a dedicated svc and handler on KCP consuming the listener pkg
• onboarding guide is up to date and detailed enough to guide other teams how to setup the watch