bug#32733: 26; (dired-x) `Shell Command Guessing' typo

[Drew Adams]

This is not clear:

  If '*' in the shell command, that means to substitute the file name.
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^

Probably it should be something like "If `*' appears in the shell
command..." or "If there is an asterisk (`*') in the shell command..."
or "If the shell command contains `*'...".

In GNU Emacs 26.1 (build 1, x86_64-w64-mingw32)
 of 2018-05-30
Repository revision: 07f8f9bc5a51f5aa94eb099f3e15fbe0c20ea1ea
Windowing system distributor `Microsoft Corp.', version 10.0.16299
Configured using:
 `configure --without-dbus --host=x86_64-w64-mingw32
 --without-compress-install 'CFLAGS=-O2 -static -g3''