update wording based on pr review

docs/using_helm.md

@@ -477,10 +477,11 @@ accepts chart source code, and (after audit) packages those for you.
 ## Tiller, Namespaces and RBAC
 In some cases you may wish to scope Tiller or deploy multiple Tillers to a single cluster. Here are some best practices when operating in those circumstances.
 
-1. Tiller can be [installed](install.md) into any namespace. By default, it is installed into kube-system. You can run multiple tillers in multiple namespaces.
+1. Tiller can be [installed](install.md) into any namespace. By default, it is installed into kube-system. You can run multiple Tillers provided they each run in their own namespace.
 2. Limiting Tiller to only be able to install into specific namespaces and/or resource types is controlled by Kubernetes [RBAC](https://kubernetes.io/docs/admin/authorization/rbac/) roles and rolebindings.
-3. Release names are unique PER TILLER INSTANCE .
+3. Release names are unique PER TILLER INSTANCE.
 4. Charts should only contain resources that exist in a single namespace.
+5. It is not recommended to have multiple Tillers configured to manage resources in the same namespace.
 
 ## Conclusion