Update MissingValueReplacingEstimator.xml

The build team is doing test for DocFX v3 migration, the xref syntax is more strict in v3.

dotnet/xml/Microsoft.ML.Transforms/MissingValueReplacingEstimator.xml

@@ -31,7 +31,7 @@
              | Output column data type | The same as the data type in the input column |
              | Exportable to ONNX | Yes |
             
-             The resulting <xref:Microsoft.ML.Transforms.MissingValueReplacingTransformer"/> creates a new column, named as specified in the output column name parameters, and
+             The resulting <xref:Microsoft.ML.Transforms.MissingValueReplacingTransformer> creates a new column, named as specified in the output column name parameters, and
              copies the data from the input column to this new column with exception what missing values in data would be replaced according to chosen strategy.
             
              Check the See Also section for links of usage examples.