CM+B - added status codes for enterprise-api

Author: bandersmsft

articles/cost-management-billing/manage/enterprise-api.md

@@ -5,7 +5,7 @@ author: mumami
 tags: billing
 ms.service: cost-management-billing
 ms.topic: reference
-ms.date: 02/14/2020
+ms.date: 04/14/2020
 ms.author: banders
 
 ---
@@ -36,7 +36,7 @@ A Swagger endpoint is available [here](https://consumption.azure.com/swagger/ui/
 * **Reserved Instance Details** - The [Reserved Instance usage API](/rest/api/billing/enterprise/billing-enterprise-api-reserved-instance-usage) returns the usage of the Reserved Instance purchases. The [Reserved Instance charges API](/rest/api/billing/enterprise/billing-enterprise-api-reserved-instance-usage) shows the billing transactions made.
 
 ## Data Freshness
-Etags will be returned in the response of all the above API. A change in Etag indicates the data has been refreshed.  In subsequent calls to the same API using the same parameters, pass the captured Etag with the key “If-None-Match” in the header of http request. The response status code would be "NotModified" if the data has not been refreshed any further and no data will be returned. API will return the full dataset for the required period whenever there is an etag change.
+Etags will be returned in the response of all the above API. A change in Etag indicates the data has been refreshed.  In subsequent calls to the same API using the same parameters, pass the captured Etag with the key "If-None-Match" in the header of http request. The response status code would be "NotModified" if the data has not been refreshed any further and no data will be returned. API will return the full dataset for the required period whenever there is an etag change.
 
 ## Helper APIs
  **List Billing Periods** - The [Billing Periods API](/rest/api/billing/enterprise/billing-enterprise-api-billing-periods) returns a list of billing periods that have consumption data for the specified Enrollment in reverse chronological order. Each Period contains a property pointing to the API route for the four sets of data - BalanceSummary, UsageDetails, Marketplace Charges, and Price Sheet.
@@ -46,7 +46,9 @@ Etags will be returned in the response of all the above API. A change in Etag in
 |Response Status Code|Message|Description|
 |-|-|-|
 |200| OK|No error|
+|400| Bad Request| Invalid params – Date ranges, EA numbers etc.|
 |401| Unauthorized| API Key not found, Invalid, Expired etc.|
 |404| Unavailable| Report endpoint not found|
-|400| Bad Request| Invalid params – Date ranges, EA numbers etc.|
+|429 | TooManyRequests | The request was throttled. Retry after waiting for the time specified in the <code>x-ms-ratelimit-microsoft.consumption-retry-after</code> header.|
 |500| Server Error| Unexpected error processing request|
+| 503 | ServiceUnavailable | The service is temporarily unavailable. Retry after waiting for the time specified in the <code>Retry-After</code> header.|