Minor clarification in rancher provider example config.yaml

Added clarification on the URL. I made the mistake of copying the API endpoint provided in the Rancher UI when you create a token. Of course, this wrong URL generated confusing errors that took me hours to understand. 
Wishing no one in the community loses this much time as me :)

cluster-autoscaler/cloudprovider/rancher/examples/config.yaml

@@ -1,9 +1,13 @@
-# rancher server credentials
+# Rancher URL (Not API endpoint)
 url: https://rancher.example.org
+# When you create a token in the Rancher UI
+# it gives you the API endpoint, that is the Rancher URL with the /v3 appended at the end.
+# make sure the url does not contains the /v3 appended
+# rancher server credentials
 token: <rancher token>
 # name and namespace of the clusters.provisioning.cattle.io resource on the
 # rancher server
 clusterName: my-cluster
 clusterNamespace: fleet-default
 # optional, will be auto-discovered if not specified
-#clusterAPIVersion: v1alpha4
+#clusterAPIVersion: v1alpha4