Highlight the `civicrm_api3()` wrapper

ref:
https://github.com/civicrm/civicrm-dev-docs/pull/228#discussion_r130017573

docs/framework/api-architecture.md

@@ -9,7 +9,7 @@ v3](/api/index.md) page.
 ## Standards {:#standards}
 
 -   The ONLY supported way to interact with any code in the API folder
-    from outside the api folder is by using the `civicrm_api()` wrapper
+    from outside the api folder is by using the `civicrm_api()` wrapper (or preferably the `civicrm_api3()` wrapper).
 -   Functionality delivered by the API is only supported if it is
     1.  Advertised via the 'getfields function' OR (preferably AND)
     2.  Verified by a test