fix: set error_log

Signed-off-by: Adrian Nöthlich <git@promasu.tech>

Author: promasu

docker/nginx.conf

@@ -1,5 +1,3 @@
-error_log stderr;
-
 events {
   worker_connections 1024;
 }
@@ -26,6 +24,7 @@ http {
 
     include             mime.types;
     access_log          /dev/stdout;
+    error_log           /dev/stderr;
     listen              [::]:8080 ipv6only=off;
     proxy_redirect      off;
     proxy_set_header    Host                $host;