runtime(doc): fix typo synconcealend -> synconcealed (#14644)

Signed-off-by: Philip H <47042125+pheiduck@users.noreply.github.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/pattern.txt b/runtime/doc/pattern.txt
index c23462c..f16e7d2 100644
--- a/runtime/doc/pattern.txt
+++ b/runtime/doc/pattern.txt
@@ -1404,7 +1404,7 @@
 		rules.  Both methods can be used to conceal text.
 
 		Thus the matching functions like |matchadd()| won't consider
-		syntax rules and functions like |synconcealend()| and the
+		syntax rules and functions like |synconcealed()| and the
 		other way around.
 
 							*:mat* *:match*