AWS Billing Update: Clarify IPv4 and IPv6 endpoints

Author: AWS

.changes/next-release/feature-AWSBilling-fdfd053.json

@@ -0,0 +1,6 @@
+{
+    "type": "feature",
+    "category": "AWS Billing",
+    "contributor": "",
+    "description": "Clarify IPv4 and IPv6 endpoints"
+}