Fix ML.NET API docs

[gewarren]

Describe the issue or suggestion

This include syntax doesn't render properly on Learn (perhaps because the includes are within summary tags). Note that this does work in IntelliSense, so for that reason, perhaps we shouldn't work around the Learn limitation.

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