Add design decision for resource peoprety renaming

Closes #131.

docs/topics/design-decisions.rst

@@ -16,5 +16,22 @@ It is intended as a reference.
   in the same zone. By requiring the zone across the board, it is less likely to
   lead to a miss match. (Related to 63_.)
 
+- **Name property updates will result in cloud-dependent code.**
+
+  Some providers (e.g., GCE, Azure) do not allow names of resources to be
+  changed after a resource has been created. Similarly, AWS does not allow VM
+  firewall (i.e., security group) names to be changed. Providers seem to be
+  gravitating toward use of tags (or labels) to support arbitrary naming and
+  name changes. Yet, OpenStack for example, does not have a concept of resource
+  tags so CloudBridge cannot rely solely on tags. Further, tags do not need to
+  be unique across multiple resources, while names do (at least for some
+  resources, such as vmfirewalls within a private network). Overall, consistency
+  is challenging to achieve with resource renaming. With that, CloudBridge will
+  support resource renaming to the best extent possible and balance between the
+  use of resource name property and resource tags. However, because of the
+  inconsistency of rename functionality across the providers, using the rename
+  capabilities within CloudBridge will lead to cloud-dependent code. (Related to
+  131_.)
 
   .. _63: https://github.com/CloudVE/cloudbridge/issues/63
+  .. _131: https://github.com/CloudVE/cloudbridge/issues/131