in overall model file, say why you might use each engine

[topepo]

From LatinR 2023, a question points out that we don't tell people why they might use one engine over the other.

For something like linear_reg() we can briefly discuss the types of problems that would lead you to use specific engines.

[jxu]

Some have multithreaded implementations or verbose modes (showing progress) which are good to point out.