[StumpWM] Replace explicit calls to terminal by command

In order to make my dotfiles more maintainable in case I change my
terminal emulator, explicit calls to the terminal have been replaced
by calls to the function `term' which itself will call explicitely the
terminal emulator.

org/config/stumpwm.org

@@ -218,7 +218,6 @@ And it’s done! We can now move on to the creation of the other CLisp files.
 :CUSTOM_ID: Commands-1wagy001v5j0
 :header-args:lisp: :mkdirp :tangle ~/.stumpwm.d/commands.lisp
 :END:
-
 The first command I declare in this file is a command that will avoid
 me invoking too many Firefox instances. Either Firefox is not already
 running and an instance is launched, or one already is and we are
@@ -252,6 +251,16 @@ below the current frame respectively, then focus it.
               (move-focus :down))
 #+end_src
 
+Now, let’s create a command for invoking the terminal, optionally with
+a program.
+#+begin_src lisp
+  (defcommand term (&optional program) ()
+              "Invoke a terminal, possibly with a @arg{program}."
+              (run-shell-command (if program
+                                     (format nil "kitty ~A" program)
+                                     "kitty")))
+#+end_src
+
 And done! Next!
 
 * Colors
@@ -840,7 +849,7 @@ The application keymap can now be bound to the root map like so:
 I will also bind to the top map ~s-RET~ in order to open a new terminal
 window. The screenshot keymap is also bound to the ScreenPrint key.
 #+begin_src lisp
-  (define-key *top-map* (kbd "s-RET") "exec kitty")
+  (define-key *top-map* (kbd "s-RET") "term")
   (define-key *top-map* (kbd "Print") '*my-screenshot-keymap*)
 #+end_src