bug#36206: [PATCH] Change `user-error' docstring from "pilot error" to "user error"

[Drew Adams <drew.adams@oracle.com>]

> > That is unfortunately not what Wikipedia or Google will show a
> > confused user, not even when searching e.g. "pilot error software".
> > So besides hacker lore, which only a subset of our users will be very
> > familiar with, what is the benefit of using this term?
> 
> There are many terms Emacs uses, and which are not documented in
> Wikipedia.
> 
> For what is worth, I object such a change. If needed, we could give a
> general guidance in the documentation, where to search for.

FWIW, I agree with Stefan K. about this, but I
don't think it's a big deal either way.

There's nothing special or noteworthy about the
"hackerness" or the "Emacsness" of the phrase
"pilot error", and it's clearer in general to use
"user error".  We lose nothing important by doing
that.

I agree that "pilot error" describes perfectly
what's involved: the cause of the mishap (e.g.
airplane crash) was a human operator, not the
tool/equipment being operated.

But I don't think it helps to use the phrase in
the doc.  There's no need to invite confusion by
users unfamiliar with the phrase.  Just use the
perfectly clear, if less explanatory and poetic,
"user error".

(Just one opinion.)