project-prompter: Update the docstring for the recent change

* lisp/progmodes/project.el (project-prompter):
Update the docstring too (bug#70833).

1 files changed, 3 insertions, 1 deletions

diff --git a/lisp/progmodes/project.el b/lisp/progmodes/project.el
index 3cdaa7c2a76..5062021f8a6 100644
--- a/lisp/progmodes/project.el
+++ b/lisp/progmodes/project.el
@@ -199,7 +199,9 @@ When it is non-nil, `project-current' will always skip prompting too.")
 
 (defcustom project-prompter #'project-prompt-project-dir
   "Function to call to prompt for a project.
-Called with no arguments and should return a project root dir."
+The function is either called with no arguments or with one argument,
+which is the prompt string to use.  It should return a project root
+directory."
   :type '(choice (const :tag "Prompt for a project directory"
                         project-prompt-project-dir)
                  (const :tag "Prompt for a project name"