Check names outside of sheds?

[tpolecat]

From the Gitter channel:

@fthomas are there plans to check function / type names outside of tut sheds? I just stumbled about a doc where I've renamed a function but forgot to update the reference in the surrounding description. It would be awesome if tut could also check those.

Maybe a variant of the inline variable substitution people keep asking for? tut is all about aiming low, so what's the simplest thing that might work?

/cc @non