feat: improve docs and cluster dir

cluster/base/core.yaml

@@ -0,0 +1,24 @@
+---
+apiVersion: kustomize.toolkit.fluxcd.io/v1beta1
+kind: Kustomization
+metadata:
+  name: core
+  namespace: flux-system
+spec:
+  interval: 10m0s
+  path: ./cluster/core
+  prune: false
+  sourceRef:
+    kind: GitRepository
+    name: flux-system
+  decryption:
+    provider: sops
+    secretRef:
+      name: sops-gpg
+  postBuild:
+    substitute: {}
+    substituteFrom:
+    - kind: ConfigMap
+      name: cluster-settings
+    - kind: Secret
+      name: cluster-secrets