Replace non-existant TextKey with WindowTextKey

Author: jcansdale

src/GitHub.VisualStudio.UI/Styles/Markdown.xaml

@@ -43,13 +43,13 @@
     <Setter Property="Padding" Value="4"/>
   </Style>
   <Style TargetType="{x:Type Paragraph}" x:Key="{x:Static markdig:Styles.CodeBlockStyleKey}">
-    <Setter Property="Foreground" Value="{DynamicResource {x:Static shell:VsBrushes.TextKey}}" />
+    <Setter Property="Foreground" Value="{DynamicResource {x:Static shell:VsBrushes.WindowTextKey}}" />
     <Setter Property="Background" Value="{DynamicResource GitHubBranchNameBackgroundBrush}" />
     <Setter Property="Padding" Value="2" />
     <Setter Property="FontFamily" Value="Consolas, Lucida Sans Typewriter, Courier New" />
   </Style>
   <Style TargetType="{x:Type Run}" x:Key="{x:Static markdig:Styles.CodeStyleKey}">
-    <Setter Property="Foreground" Value="{DynamicResource {x:Static shell:VsBrushes.TextKey}}" />
+    <Setter Property="Foreground" Value="{DynamicResource {x:Static shell:VsBrushes.WindowTextKey}}" />
     <Setter Property="Background" Value="{DynamicResource GitHubBranchNameBackgroundBrush}" />
     <Setter Property="FontFamily" Value="Consolas, Lucida Sans Typewriter, Courier New" />
   </Style>