Use installed apiversion

I gathered this by using `kubectl api-resources | grep -i helmrelease`

cluster/home/longhorn-system/longhorn-helm.yml

@@ -1,4 +1,4 @@
-apiVersion: helm.fluxcd.io/v1
+apiVersion: helm.toolkit.fluxcd.io/v2beta1
 kind: HelmRelease
 metadata:
   name: longhorn

readme.md

@@ -28,6 +28,9 @@ Before we interact with the cluster, we have some manual work to do.
     - Have `python3` installed
     - Need to be `ssh`-able from a controller (my workstation)
       - `curl -L files.lyte.dev/key.pub >> ~/.ssh/authorized_keys`
+  - Nodes must support Longhorn: https://longhorn.io/docs/1.2.3/deploy/install/#installation-requirements
+    - Nodes must be running on a host filesystem that supports `file extents`
+    - Provisioning takes care of the rest
 
 ### Automated Provisioning