Issues with LoadFromEnumerable documentation

https://review.docs.microsoft.com/en-us/dotnet/api/microsoft.ml.dataoperationscatalog.loadfromenumerable?view=ml-dotnet&branch=smoke-test-preview

>IEnumerable enumerableOfData = DatasetUtils.GetSampleTemperatureData(5);

We should show how original class looks like. We should show what we can work on properties and fields. Which current sample is lacking. It's also doesn't show how to use `SchemaDefinition`

>LoadFromEnumerable(IEnumerable, DataViewSchema)

That method lacks sample.

https://review.docs.microsoft.com/en-us/dotnet/api/microsoft.ml.dataviewschema.column.tostring?view=ml-dotnet&branch=smoke-test-preview#Microsoft_ML_DataViewSchema_Column_ToString

Would be nice to document.

https://review.docs.microsoft.com/en-us/dotnet/api/microsoft.ml.data.schemadefinition.create?view=ml-dotnet&branch=smoke-test-preview#Microsoft_ML_Data_SchemaDefinition_Create_System_Type_Microsoft_ML_Data_SchemaDefinition_Direction_
`SchemaDefinition` is quite lacking documentation.