runtime(doc): document proper notation of gVim, document vim-security list

Also, while at it, document the vim-security mailing list.

closes: #13429

Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/doc/intro.txt

@@ -1,4 +1,4 @@
-*intro.txt*     For Vim version 9.0.  Last change: 2023 Aug 15
+*intro.txt*     For Vim version 9.0.  Last change: 2023 Nov 18
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -43,7 +43,8 @@ document, there is a separate document for each supported system, see
 
 							*pronounce*
 Vim is pronounced as one word, like Jim, not vi-ai-em.  It's written with a
-capital, since it's a name, again like Jim.
+capital, since it's a name, again like Jim.  The GUI version of Vim is written
+"gVim" (or "GVim" when at the beginning of a sentence).
 
 This manual is a reference for all the Vim commands and options.  This is not
 an introduction to the use of Vi or Vim, it gets a bit complicated here and
@@ -97,12 +98,14 @@ There are several mailing lists for Vim:
 <vim-mac@vim.org>				*vim-mac* *vim_mac*
 	For discussions about using and improving the Macintosh version of
 	Vim.
+<vim-security@googlegroups.com>			*vim-security*
+	This list is for (privately) discussing security relevant issues of Vim.
 
 See http://www.vim.org/maillist.php for the latest information.
 
 NOTE:
 - Anyone can see the archive, e.g. on Google groups.  Search this if you have
-  questions.
+  questions, except for the vim-security list.
 - You can only send messages to these lists if you have subscribed!
 - The first message is moderated, thus it may take a few hours to show up.
 - You need to send the messages from the same location as where you subscribed

runtime/doc/tags

@@ -10999,6 +10999,7 @@ vim-modes-intro	intro.txt	/*vim-modes-intro*
 vim-raku	ft_raku.txt	/*vim-raku*
 vim-script-intro	usr_41.txt	/*vim-script-intro*
 vim-script-library	eval.txt	/*vim-script-library*
+vim-security	intro.txt	/*vim-security*
 vim-use	intro.txt	/*vim-use*
 vim-variable	eval.txt	/*vim-variable*
 vim.b	if_lua.txt	/*vim.b*