cluster/README.md: update notes about content

- Adjust the link to point at https://kubernetes.io/docs/setup/
to alternative solutions.
https://kubernetes.io/docs/getting-started-guides already redirects to
https://kubernetes.io/docs/setup/ and it does not contain details on
/cluster usage.
- Remove notes about the contents of the folder, leaving only the
deprecation notice and link to alternatives.

Author: neolit123

cluster/README.md

@@ -2,11 +2,6 @@
 
 ##### Deprecation Notice: This directory has entered maintenance mode and will not be accepting new providers. Deployments in this directory will continue to be maintained and supported at their current level of support.
 
-The scripts and data in this directory automate creation and configuration of a Kubernetes cluster, including networking, DNS, nodes, and control plane components.
-
-See the [getting-started guides](https://kubernetes.io/docs/getting-started-guides) for examples of how to use the scripts.
-
-*cloudprovider*/`config-default.sh` contains a set of tweakable definitions/parameters for the cluster.
-
+See the [Getting started](https://kubernetes.io/docs/setup/) guide for alternatives.
 
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