fix copyright and secret manager link

Author: jdpedrie

cloud_sql/postgres/pdo/app-standard.yaml

@@ -1,4 +1,4 @@
-# Copyright 2018 Google LLC
+# Copyright 2020 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -15,7 +15,7 @@
 runtime: php72
 
 # Remember - storing secrets in plaintext is potentially unsafe. Consider using
-# something like https://cloud.google.com/kms/ to help keep secrets secret.
+# something like https://cloud.google.com/secret-manager/ to help keep secrets secret.
 env_variables:
   CLOUD_SQL_CONNECTION_NAME: ::
   DB_USER: my-db-user