fix link to other werk

Change-Id: I645b3c62968b36ff0f43c6380069fea889f80c27

Author: BenediktSeidl

.werks/18300.md

@@ -18,4 +18,4 @@ regex compile, the code fell through to hostname validation, which
 rightfully refused the regex as a host name.
 
 Valid regex patterns are now accepted again. Invalid ones still produce
-a clear error message, as intended by werk #18988.
+a clear error message, as intended by werk #18491.