runtime(doc): fix typo in tag for helptoc package

Co-authored-by: Hirohito Higashi <h.east.727@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/helphelp.txt b/runtime/doc/helphelp.txt
index 4e08d90..4af6efd 100644
--- a/runtime/doc/helphelp.txt
+++ b/runtime/doc/helphelp.txt
@@ -1,4 +1,4 @@
-*helphelp.txt*	For Vim version 9.1.  Last change: 2025 May 04
+*helphelp.txt*	For Vim version 9.1.  Last change: 2025 May 31
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -305,8 +305,9 @@
 <Esc> instead of <CR>, you can then get more context for each remaining entry
 by pressing `J` or `K`.
 
-Refer |helptoc.vim| for more details about helptoc, particularly about using
-it with filetypes other than help, and configuring its options.
+Refer to |helptoc.txt| for more details about helptoc, particularly about
+using it with filetypes other than help, and configuring its options.
+Note:  You need to `packadd helptoc` before you can jump to |helptoc.txt|.
 
 ==============================================================================
 2. Translated help files				*help-translated*