runtime(vim): fix incorrect highlighting of User autocmds

There is no pattern after the user event name. The user event name is
the pattern.

closes: #17568

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Doug Kearns <dougkearns@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/syntax/vim.vim b/runtime/syntax/vim.vim
index fe50133..10cefd3 100644
--- a/runtime/syntax/vim.vim
+++ b/runtime/syntax/vim.vim
@@ -2,7 +2,7 @@
 " Language:	   Vim script
 " Maintainer:	   Hirohito Higashi <h.east.727 ATMARK gmail.com>
 "	   Doug Kearns <dougkearns@gmail.com>
-" Last Change:	   2025 Jun 11
+" Last Change:	   2025 Jun 18
 " Former Maintainer: Charles E. Campbell
 
 " DO NOT CHANGE DIRECTLY.
@@ -121,7 +121,7 @@
 syn keyword vimAutoEvent contained WinScrolled skipwhite nextgroup=vimAutoEventSep,@vimAutocmdPattern
 
 syn keyword	vimAutoEvent	contained	User	skipwhite nextgroup=vimUserAutoEvent
-syn match	vimUserAutoEvent	contained	"\<\h\w*\>"	skipwhite nextgroup=vimAutoEventSep,@vimAutocmdPattern
+syn match	vimUserAutoEvent	contained	"\<\h\w*\>"	skipwhite nextgroup=vimUserAutoEventSep,vimAutocmdMod,vimAutocmdBlock
 
 " Highlight commonly used Groupnames {{{2
 syn keyword vimGroup contained	Comment Constant String Character Number Boolean Float Identifier Function Statement Conditional Repeat Label Operator Keyword Exception PreProc Include Define Macro PreCondit Type StorageClass Structure Typedef Special SpecialChar Tag Delimiter SpecialComment Debug Underlined Ignore Error Todo
@@ -1260,6 +1260,7 @@
 " higher priority than vimAutocmdGroup, assume no group is so named
 syn match	vimAutoEventGlob	contained	"*"	skipwhite nextgroup=@vimAutocmdPattern
 syn match	vimAutoEventSep	contained	"\a\@1<=,"	nextgroup=vimAutoEvent
+syn match	vimUserAutoEventSep contained	"\a\@1<=,"	nextgroup=vimUserAutoEvent
 
 syn match	vimAutocmd		"\<au\%[tocmd]\>"	skipwhite nextgroup=vimAutocmdBang,vimAutocmdGroup,vimAutoEvent,vimAutoEventGlob