patch 9.1.0864: message history is fixed to 200

Problem:  message history is fixed to 200
Solution: Add the 'msghistory' option, increase the default
          value to 500 (Shougo Matsushita)

closes: #16048

Co-authored-by: Milly <milly.ca@gmail.com>
Signed-off-by: Shougo Matsushita <Shougo.Matsu@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/version9.txt b/runtime/doc/version9.txt
index ac0700e..10e13f8 100644
--- a/runtime/doc/version9.txt
+++ b/runtime/doc/version9.txt
@@ -1,4 +1,4 @@
-*version9.txt*  For Vim version 9.1.  Last change: 2024 Nov 11
+*version9.txt*  For Vim version 9.1.  Last change: 2024 Nov 14
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -41659,6 +41659,7 @@
 			popup
 'findfunc'		Vim function to obtain the results for a |:find|
 			command
+'msghistory'		Max number of messages to remember
 'winfixbuf'		Keep buffer focused in a window
 'tabclose'		Which tab page to focus after closing a tab page
 't_xo'			Terminal uses XON/XOFF handshaking (e.g. vt420)