cluster/kube: split up cluster.jsonnet

It was getting large and unwieldy (to the point where kubecfg was slow).
In this change, we:

 - move the Cluster function to cluster.libsonnet
 - move the Cluster instantiation into k0.libsonnet
 - shuffle some fields around to make sure things are well split between
   k0-specific and general cluster configs.
 - add 'view' files that build on 'cluster.libsonnet' to allow rendering
   either the entire k0 state, or some subsets (for speed)
 - update the documentation, drive-by some small fixes and reindantation

Change-Id: I4b8d920b600df79100295267efe21b8c82699d5b
diff --git a/cluster/kube/k0-ceph.jsonnet b/cluster/kube/k0-ceph.jsonnet
new file mode 100644
index 0000000..bc025d4
--- /dev/null
+++ b/cluster/kube/k0-ceph.jsonnet
@@ -0,0 +1,8 @@
+// Ceph operator (rook), pools, users.
+
+local k0 = (import "k0.libsonnet").k0;
+
+{
+    rook: k0.cluster.rook,
+    ceph: k0.ceph,
+}