remove linkerd-base references (#13323)

charts/linkerd-control-plane/README.md

@@ -48,9 +48,6 @@ Note that the provided certificates must be ECDSA certificates.
 
 ## Adding Linkerd's Helm repository
 
-Included here for completeness-sake, but should have already been added when
-`linkerd-base` was installed.
-
 ```bash
 # To add the repo for Linkerd edge releases:
 helm repo add linkerd https://helm.linkerd.io/edge
@@ -69,9 +66,6 @@ helm install linkerd-control-plane -n linkerd \
   linkerd/linkerd-control-plane
 ```
 
-Note that you require to install this chart in the same namespace you installed
-the `linkerd-base` chart.
-
 ## Setting High-Availability
 
 Besides the default `values.yaml` file, the chart provides a `values-ha.yaml`