credit card fraud print more decimals for accuracy (dotnet#268)

Merging this PR into master

Author: kevmal

samples/fsharp/getting-started/BinaryClassification_CreditCardFraudDetection/CreditCardFraudDetection/Program.fs

@@ -204,7 +204,7 @@ let main _ =
     let model = pipeline.Fit trainData
 
     let metrics = classification.Evaluate (model.Transform (testData), "Label")   
-    printfn "Accuracy: %.2f" metrics.Accuracy 
+    printfn "Accuracy: %.12f" metrics.Accuracy 
 
     printfn "Saving model to file"
     let _ =