Added icon image to package

Author: islero

src/Backtest.Net/Backtest.Net.csproj

@@ -19,10 +19,7 @@
 
   <ItemGroup>
     <None Include="..\..\README.md" Pack="true" PackagePath="\" />
-    <None Update="icon.png">
-      <Pack>True</Pack>
-      <PackagePath></PackagePath>
-    </None>
+    <None Include="images\icon.png" Pack="true" PackagePath="\" />
   </ItemGroup>
 
   <ItemGroup>