add 15dot8dot2 preview data

Author: tglee

docs/install/visual-studio-build-numbers-and-release-dates.md

@@ -5,7 +5,7 @@ keywords:
 author: TerryGLee
 ms.author: tglee
 manager: douge
-ms.date: 05/21/2018
+ms.date: 05/31/2018
 ms.topic: reference
 helpviewer_keywords:
 ms.prod: visual-studio-dev15
@@ -19,6 +19,7 @@ The following table lists the build numbers and release dates for Visual Studio
 
 | **Version**| **Channel** | **Release date** | **Build version** |
 | ---------------------- | ----------- | ---------------- | ----------------- |
+| 15.8.0 Preview 2.0 | Preview | May 31, 2018 | 15.8.27729.1 |
 | 15.7.2 | Release | May 21, 2018 | 15.7.27703.2018 |
 | 15.8.0 Preview 1.1 | Preview | May 8, 2018 | 15.8.27705.2000 |
 | 15.7.1 | Release | May 8, 2018 | 15.7.27703.2000 |