fix config path

linux/debian/files/mysqld_exporter.service

@@ -7,7 +7,7 @@ Wants=network-online.target
 Restart=always
 Type=simple
 User=mysql
-ExecStart=/usr/local/bin/mysqld_exporter --config.my-cnf=/etc/.my.cnf
+ExecStart=/usr/local/bin/mysqld_exporter --config.my-cnf=/etc/mysql/my.cnf
 Environment=
 
 [Install]