add NuGet.config

Author: Brano5

NuGet.config

@@ -10,6 +10,7 @@
     <packageSource key="gh-packages-inxton">
       <package pattern="AXSharp.*"/>
       <package pattern="AXOpen.*"/>
+      <package pattern="Inxton.Operon" />
     </packageSource>
 
     <!-- Get all other packages from nuget.org -->