Fix 'kubefed join' help string
It previously referred to an aggregated federation API server.
@@ -49,8 +49,8 @@ var (
Join adds a cluster to a federation.
Current context is assumed to be a Kubernetes cluster
- with an aggregated federation API server. Please use
- the --host-cluster-context flag otherwise.`
+ hosting the federation control plane. Please use the
+ --host-cluster-context flag otherwise.`
join_example = `
# Join a cluster to a federation by specifying the
# cluster name and the context name of the federation
