Backport commit 3f9f3ba43 from Emacs

* lisp/org-timer.el (org-timer-set-timer):
* lisp/ox.el (org-export-dispatch-last-position): Use command
substitution for 'universal-argument' instead of raw "C-u".

Docfix: use command substitution for 'universal-argument'
3f9f3ba4370bd4d0f33392befb35328327d73b1e
Stefan Kangas
Thu Sep 16 20:05:48 2021 +0200

lisp/org-timer.el

@@ -400,16 +400,16 @@ prompt the user if she wants to replace it.
 Called with a numeric prefix argument, use this numeric value as
 the duration of the timer in minutes.
 
-Called with a `C-u' prefix arguments, use `org-timer-default-timer'
+Called with a \\[universal-argument] prefix arguments, use `org-timer-default-timer'
 without prompting the user for a duration.
 
-With two `C-u' prefix arguments, use `org-timer-default-timer'
+With two \\[universal-argument] prefix arguments, use `org-timer-default-timer'
 without prompting the user for a duration and automatically
 replace any running timer.
 
 By default, the timer duration will be set to the number of
 minutes in the Effort property, if any.  You can ignore this by
-using three `C-u' prefix arguments."
+using three \\[universal-argument] prefix arguments."
   (interactive "P")
   (when (and org-timer-start-time
 	     (not org-timer-countdown-timer))

lisp/ox.el

@@ -294,7 +294,7 @@ and its CDR is a list of export options.")
 
 (defvar org-export-dispatch-last-position (make-marker)
   "The position where the last export command was created using the dispatcher.
-This marker will be used with `C-u C-c C-e' to make sure export repetition
+This marker will be used with `\\[universal-argument] C-c C-e' to make sure export repetition
 uses the same subtree if the previous command was restricted to a subtree.")
 
 ;; For compatibility with Org < 8