docs: add CLI help

docs/cmd/tk_sync_kustomization.md

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+## tk sync kustomization
+
+Synchronize kustomization
+
+### Synopsis
+
+
+The sync kustomization command triggers a reconciliation of a Kustomization resource and waits for it to finish.
+
+```
+tk sync kustomization [name] [flags]
+```
+
+### Examples
+
+```
+  # Trigger a kustomization apply outside of the reconciliation interval
+  sync kustomization podinfo
+
+  # Trigger a git sync of the kustomization source and apply changes
+  sync kustomization podinfo --with-source
+
+```
+
+### Options
+
+```
+  -h, --help          help for kustomization
+      --with-source   synchronize kustomization source
+```
+
+### Options inherited from parent commands
+
+```
+      --components strings   list of components, accepts comma-separated values (default [source-controller,kustomize-controller])
+      --kubeconfig string    path to the kubeconfig file (default "~/.kube/config")
+      --namespace string     the namespace scope for this operation (default "gitops-system")
+      --timeout duration     timeout for this operation (default 5m0s)
+      --verbose              print generated objects
+```
+
+### SEE ALSO
+
+* [tk sync](tk_sync.md)	 - Synchronize commands
+
+###### Auto generated by spf13/cobra on 30-Apr-2020