docs(vcluster): add CAPIVC reference link

Reviewer requested reference to CAPIVC project. Added direct
link to the cluster-api-provider-vcluster GitHub repository.

Author: Piotr1215

vcluster/learn-how-to/control-plane/container/configure-webhook-token-auth.mdx

@@ -195,7 +195,7 @@ The webhook must respond with the authentication result:
 
 ## Use with CAPIVC
 
-When using vCluster with CAPIVC, you can configure webhook token authentication through the `VCLUSTER_YAML` environment variable:
+When using vCluster with [Cluster API Provider for vCluster (CAPIVC)](https://github.com/loft-sh/cluster-api-provider-vcluster), you can configure webhook token authentication through the `VCLUSTER_YAML` environment variable:
 
 ```bash
 cat > /tmp/values.yaml <<EOF