Ensembler not shown as best pipeline in automl ensemble docs

The [automl ensembling user guide](https://evalml.alteryx.com/en/stable/user_guide/automl.html?highlight=ensembl#Adding-ensemble-methods-to-AutoML) says
> We can view more information about the stacking ensemble pipeline (which was the best performing pipeline) by calling .describe().

but the pipeline chosen as the best is the Elastic Net Classifier.

@christopherbunn FYI :)