Update cookbook (#2494)

* Switch OneHotEncoding parameters

* Fix table of contents

* Update for spacing

Author: jwood803

docs/code/MlNetCookBook.md

@@ -688,11 +688,11 @@ var catColumns = data.GetColumn<string[]>(mlContext, "CategoricalFeatures").Take
 // Build several alternative featurization pipelines.
 var pipeline =
     // Convert each categorical feature into one-hot encoding independently.
-    mlContext.Transforms.Categorical.OneHotEncoding("CategoricalFeatures", "CategoricalOneHot")
+    mlContext.Transforms.Categorical.OneHotEncoding("CategoricalOneHot", "CategoricalFeatures")
     // Convert all categorical features into indices, and build a 'word bag' of these.
-    .Append(mlContext.Transforms.Categorical.OneHotEncoding("CategoricalFeatures", "CategoricalBag", CategoricalTransform.OutputKind.Bag))
+    .Append(mlContext.Transforms.Categorical.OneHotEncoding("CategoricalBag", "CategoricalFeatures", CategoricalTransform.OutputKind.Bag))
     // One-hot encode the workclass column, then drop all the categories that have fewer than 10 instances in the train set.
-    .Append(mlContext.Transforms.Categorical.OneHotEncoding("Workclass", "WorkclassOneHot"))
+    .Append(mlContext.Transforms.Categorical.OneHotEncoding("WorkclassOneHot", "Workclass"))
     .Append(mlContext.Transforms.FeatureSelection.CountFeatureSelectingEstimator("WorkclassOneHot", "WorkclassOneHotTrimmed", count: 10));
 
 // Let's train our pipeline, and then apply it to the same data.