patch 9.1.1419: It is difficult to ignore all but some events

Problem:  It is difficult to ignore all but some events.
Solution: Add support for a "-" prefix syntax in '(win)eventignore' that
          subtracts an event from the ignored set if present
          (Luuk van Baal).

closes: #17392

Signed-off-by: Luuk van Baal <luukvbaal@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index 47f56c0..d69c204 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -1,4 +1,4 @@
-*options.txt*	For Vim version 9.1.  Last change: 2025 May 30
+*options.txt*	For Vim version 9.1.  Last change: 2025 May 31
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -3377,6 +3377,9 @@
 	Otherwise this is a comma-separated list of event names.  Example: >
 	    :set ei=WinEnter,WinLeave
 <
+	To ignore all but some events, a "-" prefix can be used: >
+	    :set ei=all,-WinLeave
+<
 						*'eventignorewin'* *'eiw'*
 'eventignorewin' 'eiw'	string	(default "")
 			window-local