Fix README.md path in project file for packaging

Author: jongalloway

src/NLWebNet/NLWebNet.csproj

@@ -63,7 +63,7 @@
 	<ItemGroup>
 		<FrameworkReference Include="Microsoft.AspNetCore.App" />
 	</ItemGroup>	<ItemGroup>
-		<None Include="..\..\README.md" Pack="true" PackagePath="\" />
+		<None Include="$(MSBuildProjectDirectory)\..\..\README.md" Pack="true" PackagePath="\" />
 	</ItemGroup>
 
 </Project>