Removed random class diagram.

src/Avalonia.Visuals/Avalonia.Visuals.csproj

@@ -191,7 +191,6 @@
     <Compile Include="VisualTree\VisualExtensions.cs" />
   </ItemGroup>
   <ItemGroup>
-    <None Include="ClassDiagram1.cd" />
     <None Include="packages.config" />
   </ItemGroup>
   <ItemGroup>