runtime(help): highlight CTRL-<Key> correctly

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/syntax/help.vim b/runtime/syntax/help.vim
index 913b1de..ff214e2 100644
--- a/runtime/syntax/help.vim
+++ b/runtime/syntax/help.vim
@@ -1,7 +1,7 @@
 " Vim syntax file
 " Language:	Vim help file
 " Maintainer:	The Vim Project <https://github.com/vim/vim>
-" Last Change:	2024 Oct 05
+" Last Change:	2024 Oct 08
 " Former Maintainer:	Bram Moolenaar <Bram@vim.org>
 
 " Quit when a (custom) syntax file was already loaded
@@ -97,6 +97,7 @@
 syn match helpNormal		"\[\(readonly\|fifo\|socket\|converted\|crypted\)]"
 
 syn match helpSpecial		"CTRL-."
+syn match helpSpecial		"CTRL-<\a\+>"
 syn match helpSpecial		"CTRL-SHIFT-."
 syn match helpSpecial		"CTRL-Break"
 syn match helpSpecial		"CTRL-PageUp"