Merge pull request #103242 from Juliako/patch-180

Update release-notes.md

Author: PRMerger8

articles/media-services/latest/release-notes.md

@@ -11,7 +11,7 @@ editor: ''
 ms.service: media-services
 ms.workload: na
 ms.topic: article
-ms.date: 12/13/2019
+ms.date: 02/03/2020
 ms.author: juliako
 ---
 
@@ -32,14 +32,33 @@ To stay up-to-date with the most recent developments, this article provides you
 > Currently, you cannot use the Azure portal to manage v3 resources. Use the [REST API](https://aka.ms/ams-v3-rest-sdk), CLI, or one of the supported SDKs.
 
 For more information, see [Migration guidance for moving from Media Services v2 to v3](migrate-from-v2-to-v3.md#known-issues).
-
+ 
 ## January 2020
 
 ### Improvements in media processors
 
 - Improved support for interlaced sources in Video Analysis – such content is now de-interlaced correctly before being sent to inference engines.
 - When generating thumbnails with the “Best” mode, the encoder now searches beyond 30 seconds to select a frame that is not monochromatic.
- 
+
+### Azure Government cloud updates
+
+Media Services GA’ed in the following Azure Government regions: *USGov Arizona* and *USGov Texas*.
+
+## December 2019
+
+Added CDN support for *Origin-Assist Prefetch* headers for both live and video on-demand streaming; available for customers who have direct contract with Akamai CDN. Origin-Assist CDN-Prefetch feature involves the following HTTP header exchanges between Akamai CDN and Azure Media Services origin:
+
+|HTTP header|Values|Sender|Receiver|Purpose|
+| ---- | ---- | ---- | ---- | ----- |
+|CDN-Origin-Assist-Prefetch-Enabled | 1 (default) or 0 |CDN|Origin|To indicate CDN is prefetch enabled|
+|CDN-Origin-Assist-Prefetch-Path| Example: <br/>Fragments(video=1400000000,format=mpd-time-cmaf)|Origin|CDN|To provide prefetch path to CDN|
+|CDN-Origin-Assist-Prefetch-Request|1 (prefetch request) or 0 (regular request)|CDN|Origin|To indicate the request from CDN is a prefetch|
+
+To see part of the header exchange in action, you can try the following steps:
+
+1. Use Postman or curl to issue a request to Media Services origin for an audio or video segment or fragment. Make sure to add the header CDN-Origin-Assist-Prefetch-Enabled: 1 in the request.
+2. In the response, you should see the header CDN-Origin-Assist-Prefetch-Path with a relative path as its value.
+
 ## November 2019
 
 ### Live transcription Preview