update the Update dates on updated docs

Author: TerryGLee

docs/ide/code-snippets-schema-reference.md

@@ -1,6 +1,6 @@
 ---
 title: Code snippets schema reference
-ms.date: 02/25/2019
+ms.date: 03/31/2020
 ms.topic: reference
 helpviewer_keywords:
 - schema reference [Visual Studio]

docs/ide/connect-team-project.md

@@ -1,6 +1,6 @@
 ---
 title: Connect to projects in Team Explorer
-ms.date: 12/04/2018
+ms.date: 03/31/2020
 ms.topic: conceptual
 ms.author: tglee
 author: TerryGLee

docs/ide/visual-studio-multi-targeting-overview.md

@@ -1,6 +1,6 @@
 ---
 title: Targeted .NET frameworks
-ms.date: 02/06/2018
+ms.date: 03/31/2020
 ms.topic: conceptual
 helpviewer_keywords:
 - targeting .NET Framework [Visual Studio]

docs/ide/walkthrough-creating-a-code-snippet.md

@@ -1,6 +1,6 @@
 ---
 title: 'Walkthrough: Create a code snippet'
-ms.date: 06/10/2019
+ms.date: 03/31/2020
 ms.topic: conceptual
 helpviewer_keywords:
 - code snippets, creating