Hello,

Here is a new revision of this patch series, which aims to rephrase
dired-do-shell-command's warning about occurrences of '?' and '*' that
will not be substituted for filenames, with the following goals in mind:

1. cease to call these characters "wildcards" since they may be quoted
   or escaped,
2. cater to users who do not know about the substitution feature,
3. keep the default prompt as concise as the current one.

The first revisions[1][2][3][4] focused on goals 1 and 2, to the
detriment of 3.  The last revision[5] hid the verbosity behind an
optional explanatory buffer, using read-multiple-choice.  Since this
function already generates a help buffer bound to '?', I bound the
explanatory buffer to 'd' for "details", a la nsm-query-user.

Juri suggested[6] that read-char-from-minibuffer might fit the bill
better.  Since I feel kind of torn between these options, I'm putting
them both forward.

First, the scaffolding patches (same as v5):