chore: mention exception for var substitution

README.md

@@ -278,7 +278,7 @@ If Terraform was ran successfully you can log into Cloudflare and validate the D
         --from-file=age.agekey=/dev/stdin
     ```
 
-    📍 Variables defined in `./cluster/base/cluster-secrets.sops.yaml` and `./cluster/base/cluster-settings.yaml` will be usable anywhere in your YAML manifests under `./cluster`
+    📍 Variables defined in `./cluster/base/cluster-secrets.sops.yaml` and `./cluster/base/cluster-settings.yaml` will be usable anywhere in your YAML manifests under `./cluster` except `./cluster/base`
 
 4. **Verify** the `./cluster/base/cluster-secrets.sops.yaml` and `./cluster/core/cert-manager/secret.sops.yaml` files are **encrypted** with SOPS