patch 9.1.0277: Cannot highlight the Command-line

Problem:  Cannot highlight the Command-line
Solution: Add the MsgArea highlighting group
          (Shougo Matsushita)

closes: #14327

Signed-off-by: Shougo Matsushita <Shougo.Matsu@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/doc/syntax.txt

@@ -2485,7 +2485,7 @@ To specify elements that should not be concealed, set the following variable: >
 
 This is a list of the rules wich can be used here:
 
-  - titleblock 
+  - titleblock
   - image
   - block
   - subscript
@@ -5585,6 +5585,9 @@ MessageWindow	Messages popup window used by `:echowindow`.  If not defined
 		|hl-WarningMsg| is used.
 							*hl-ModeMsg*
 ModeMsg		'showmode' message (e.g., "-- INSERT --").
+							*hl-MsgArea*
+MsgArea		Command-line area, also used for outputting messages, see also
+		'cmdheight'
 							*hl-MoreMsg*
 MoreMsg		|more-prompt|
 							*hl-NonText*

runtime/doc/tags

@@ -8050,6 +8050,7 @@ hl-Menu	syntax.txt	/*hl-Menu*
 hl-MessageWindow	syntax.txt	/*hl-MessageWindow*
 hl-ModeMsg	syntax.txt	/*hl-ModeMsg*
 hl-MoreMsg	syntax.txt	/*hl-MoreMsg*
+hl-MsgArea	syntax.txt	/*hl-MsgArea*
 hl-NonText	syntax.txt	/*hl-NonText*
 hl-Normal	syntax.txt	/*hl-Normal*
 hl-Pmenu	syntax.txt	/*hl-Pmenu*

runtime/doc/version9.txt

@@ -1,4 +1,4 @@
-*version9.txt*  For Vim version 9.1.  Last change: 2024 Mar 28
+*version9.txt*  For Vim version 9.1.  Last change: 2024 Apr 08
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -41581,6 +41581,10 @@ Autocommands: ~
 |WinNewPre|		before creating a new window
 
 
+Highlighting: ~
+
+|hl-MsgArea|		highlighting of the Command-line and messages area.
+
 Commands: ~