bug#63875: 26.3; Doc of `dired-guess-shell-alist-user'

[Juri Linkov]

> Maybe say something similar to what oantolin says
> in this Reddit post:
>
>   "an alist that maps filename regexps to a list
>    of commands you might want to apply to the file."
>
> https://www.reddit.com/r/emacs/comments/13yrk5k/is_there_a_package_for_a_opening_a_menu_of_file/jmprpp2/

The request was:

  "I was thinking of something similar to OS file managers, where you can
  right-click a file and have operations relevant to the extension pop up."

So does it makes sense to add to the context menu in Dired a submenu
like this?

  "Open with ..." ->
    "Command 1"
    "Command 2"
    ...