Define acronym

Author: wsugarman

articles/healthcare-apis/dicom/index.yml

@@ -66,7 +66,7 @@ landingContent:
             url: configure-customer-managed-keys.md
           - text: Configure cross-origin resource sharing (CORS)
             url: configure-cross-origin-resource-sharing.md
-          - text: Configure Azure RBAC
+          - text: Configure Azure Role-Based Access Control (RBAC)
             url: dicom-configure-azure-rbac.md
           - text: Enable audit and diagnostic logging
             url: enable-diagnostic-logging.md