Revert sort prompt labels. (see #3930)

Revert sort prompt labels. (see #3930)

Using the (s)ort style may look a bit better, but it makes the prompt
over 80 columns.  The multichoice prompt supports multiple lines now,
but it is better to have it fit on one line if possible.

Revert back to the "capital letter" method, but leave the ticket open,
to explore other ideas that Vincent and chdiza have for better ways to
present a long choice like this.