fix(docs): Update the version to make the example work (#2156)

The feature is in beta only.

Signed-off-by: Oliver Gondža <ogondza@gmail.com>

Author: olivergondza

docs/reference/argocd.md

@@ -1087,7 +1087,7 @@ spec:
 The operator permits injecting custom TLS certificates into the Repo Server container and Config Management Plugins (sidecar containers):
 
 ```yaml
-apiVersion: argoproj.io/v1alpha1
+apiVersion: argoproj.io/v1beta1
 kind: ArgoCD
 metadata:
   name: example-argocd