readme: simplify clusterctl setup

Author: schrej

README.md

@@ -15,14 +15,7 @@ IPAM providers allow to control how IP addresses are assigned to Cluster API Mac
 
 ## Setup via clusterctl
 
-This provider comes with clusterctl support. Since it's not added to the built-in list of providers yet, you'll need to add the following to your `$XDG_CONFIG_HOME/cluster-api/clusterctl.yaml` if you want to install it using `clusterctl init --ipam in-cluster`:
-
-```yaml
-providers:
-  - name: in-cluster
-    url: https://github.com/kubernetes-sigs/cluster-api-ipam-provider-in-cluster/releases/latest/ipam-components.yaml
-    type: IPAMProvider
-```
+This provider comes with clusterctl support and can be installed using `clusterctl init --ipam in-cluster`:
 
 ## Usage