org-babel: make org-babel-tangle-file interactive

contrib/babel/lisp/org-babel-tangle.el

@@ -62,6 +62,7 @@ file using `load-file'."
 specify a default export file for all source blocks.  Optional
 argument LANG can be used to limit the exported source code
 blocks by language."
+  (interactive "f")
   (save-window-excursion (find-file file) (org-babel-tangle target-file lang)))
 
 (defun org-babel-tangle (&optional target-file lang)