Include README via Include= rather than Update=

Signed-off-by: Lamparter <[email protected]>

Author: Lamparter

src/Files.App.Controls/Files.App.Controls.csproj

@@ -54,7 +54,7 @@
     </ItemGroup>
 
     <ItemGroup>
-        <None Update="README.md">
+        <None Include="README.md">
             <Pack>True</Pack>
             <PackagePath>\</PackagePath>
         </None>