Retargeting sample. (#648)

* Retargeting sample.

* Adding tags to reference from the docs.

* Update MainPage.xaml.cs

Author: glecaros

quickstart/csharp/uwp/keyword-recognizer/helloworld/MainPage.xaml.cs

@@ -2,6 +2,7 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE.md file in the project root for full license information.
 //
+// <code>
 using System;
 using System.Collections.Generic;
 using System.IO;
@@ -170,3 +171,4 @@ private void UpdateStatus(string strMessage, NotifyType type)
         }
     }
 }
+// </code>

quickstart/csharp/uwp/keyword-recognizer/helloworld/helloworld.csproj

@@ -11,8 +11,8 @@
     <AssemblyName>helloworld</AssemblyName>
     <DefaultLanguage>en-US</DefaultLanguage>
     <TargetPlatformIdentifier>UAP</TargetPlatformIdentifier>
-    <TargetPlatformVersion Condition=" '$(TargetPlatformVersion)' == '' ">10.0.18362.0</TargetPlatformVersion>
-    <TargetPlatformMinVersion>10.0.17763.0</TargetPlatformMinVersion>
+    <TargetPlatformVersion Condition=" '$(TargetPlatformVersion)' == '' ">10.0.17134.0</TargetPlatformVersion>
+    <TargetPlatformMinVersion>10.0.16299.0</TargetPlatformMinVersion>
     <MinimumVisualStudioVersion>14</MinimumVisualStudioVersion>
     <FileAlignment>512</FileAlignment>
     <ProjectTypeGuids>{A5A43C5B-DE2A-4C0C-9213-0A381AF9435A};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>