bug#29465: 25.3; Confusing message for dired-do-shell-command substitution

[Drew Adams]

I have not been following this thread, so apologies if
this doesn't help or isn't very relevant.

IF we feel it helps a user to prompt about something,
and IF we feel there is a possibility that some users
might not understand the prompt, in spite of our best
efforts to come up with a good prompt, and IF we feel
that understanding the prompt is important, THEN the
doc string should make clear whatever it is that it
is important that users understand about that prompting.

It's quite possible for a user not to understand even
a good prompt.  S?he should be able to get the point
by doing `C-h f', in that case.