mu4e: remove example with internal function

Shouldn't promote their use.

mu4e/mu4e.texi

@@ -2371,33 +2371,18 @@ loading @t{mu4e}):
                     (mu4e-action-retag-message msg (concat "+" target)))))
 @end lisp
 
-As another example, suppose we would like to ``archive and mark read''
-a message (GMail-style), then we can run the following code (after
-loading @t{mu4e}):
-
-@lisp
-(add-to-list 'mu4e-marks
-  '(archive
-     :char       "A"
-     :prompt     "Archive"
-     :show-target (lambda (target) "archive")
-     :action      (lambda (docid msg target)
-                    ;; must come before proc-move since retag runs
-                    ;; 'sed' on the file
-                    (mu4e-action-retag-message msg "-\\Inbox")
-                    (mu4e--server-move docid nil "+S-u-N"))))
-@end lisp
-
 Adding to @code{mu4e-marks} list allows to use the mark in bulk operations
 (for example when tagging a whole thread), but does not bind the mark
 to a key to use at the top-level. This must be done separately. In our
 example:
 
 @lisp
-(mu4e~headers-defun-mark-for tag)
-(mu4e~headers-defun-mark-for archive)
+(defun my-mu4e-mark-add-tag()
+  "Add a tag to the message."
+  (interactive)
+  (mu4e-headers-mark-and-next 'tag))
+
 (define-key mu4e-headers-mode-map (kbd "g") 'mu4e-headers-mark-for-tag)
-(define-key mu4e-headers-mode-map (kbd "A") 'mu4e-headers-mark-for-archive)
 @end lisp
 
 @node Contexts