improve readme

On-behalf-of: @SAP [email protected]

Author: xrstf

README.md

@@ -5,6 +5,21 @@
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+The kcp API Sync Agent is a Kubernetes controller capable of synchronizing objects from many kcp
+workspaces onto a single Kubernetes cluster (with kcp being the source of truth). In doing so it will
+move the desired state (usually the spec) of an object from kcp to the local cluster where the agent
+is running, and move the current object status back up into kcp. The agent can also sync so-called
+related objects, like a Secret belonging to a Certificate, in both directions.
+
+The agent can be used to provide an API in kcp and then serving it from a remote Kubernetes cluster
+where the actual workload is then processed, usually by a 3rd-party operator. In many situations the
+synchronized objects are further processed using tools like Crossplane.
+
+## Documentation
+
+Please visit [https://docs.kcp.io/api-syncagent](https://docs.kcp.io/api-syncagent) for the latest
+documentation.
+
 ## Troubleshooting
 
 If you encounter problems, please [file an issue][1].