Fix broken link to coding-style.html

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: David von Oheimb <david.von.oheimb@siemens.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18015)

CONTRIBUTING.md

@@ -60,7 +60,7 @@ guidelines:
     GitHub Actions and AppVeyor are required, and they are started automatically
     whenever a PR is created or updated.
 
-    [coding style]: https://www.openssl.org/policies/codingstyle.html
+    [coding style]: https://www.openssl.org/policies/technical/coding-style.html
 
  5. When at all possible, patches should include tests. These can
     either be added to an existing test, or completely new.  Please see