runtime(doc): :ownsyntax also resets 'spelloptions'

closes: #15919

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

Author: zeertzjq

runtime/doc/syntax.txt

@@ -1,4 +1,4 @@
-*syntax.txt*	For Vim version 9.1.  Last change: 2024 Oct 20
+*syntax.txt*	For Vim version 9.1.  Last change: 2024 Oct 22
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -6142,7 +6142,8 @@ This will set the "w:current_syntax" variable to "foo".  The value of
 restoring "b:current_syntax", since the syntax files do set
 "b:current_syntax".  The value set by the syntax file is assigned to
 "w:current_syntax".
-Note: This resets the 'spell', 'spellcapcheck' and 'spellfile' options.
+Note: This resets the 'spell', 'spellcapcheck', 'spellfile' and 'spelloptions'
+options.
 
 Once a window has its own syntax, syntax commands executed from other windows
 on the same buffer (including :syntax clear) have no effect. Conversely,