Fix ML.NET API docs

[gewarren]

Describe the issue or suggestion

This include syntax doesn't render properly. Perhaps you can't have includes within summary tags.

Include works when not within another tag: https://github.com/dotnet/machinelearning/blob/d9694c4b4810efd63fc7885b9e4efdd462aee3c5/src/Microsoft.ML.TensorFlow/TensorflowCatalog.cs#L11

And it works within remarks tags: https://github.com/dotnet/machinelearning/blob/d9694c4b4810efd63fc7885b9e4efdd462aee3c5/src/Microsoft.ML.TimeSeries/IidSpikeDetector.cs#L182