Adding an example for using PFI

Author: Rogan Carr

docs/samples/Microsoft.ML.Samples/Program.cs

@@ -6,7 +6,8 @@ internal static class Program
     {
         static void Main(string[] args)
         {
-            NormalizerExample.Normalizer();
+            //NormalizerExample.Normalizer();
+            PFI_RegressionExample.PFI_Regression();
         }
     }
 }