Update copyright year

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/11616)

doc/man3/CONF_modules_free.pod

diff --git a/doc/man3/CONF_modules_free.pod b/doc/man3/CONF_modules_free.pod
index 1174bfe..dc7a117 100644
--- a/doc/man3/CONF_modules_free.pod
+++ b/doc/man3/CONF_modules_free.pod
@@ -48,7 +48,7 @@
 
 =head1 COPYRIGHT
 
-Copyright 2004-2018 The OpenSSL Project Authors. All Rights Reserved.
+Copyright 2004-2020 The OpenSSL Project Authors. All Rights Reserved.
 
 Licensed under the Apache License 2.0 (the "License").  You may not use
 this file except in compliance with the License.  You can obtain a copy