Ensemble example that shows simple univariate detector without column selector; and multiple univariate detectors *with* column selectors?

[tms-bananaquit]

Ensemble example that shows simple univariate detector without column selector; and multiple univariate detectors *with* column selectors?

[tms-bananaquit]

Taking a second look at the example, I think the narration for the StreamingEnsemble makes this clear.

Will make it just a little bit more explicit, piggybacking on an unrelated PR.