Deal with the noisy keepalive messages

We don't particularly care about HTTP... and that's what's noisy.

core/nginx/conf/nginx.conf

@@ -1,7 +1,7 @@
 # Basic configuration
 user nginx;
 worker_processes auto;
-error_log /dev/stderr info;
+error_log /dev/stderr notice;
 pid /var/run/nginx.pid;
 load_module "modules/ngx_mail_module.so";
 
@@ -252,6 +252,7 @@ mail {
     auth_http http://127.0.0.1:8000/auth/email;
     proxy_pass_error_message on;
     resolver {{ RESOLVER }} ipv6=off valid=30s;
+    error_log /dev/stderr info;
 
     {% if TLS and not TLS_ERROR %}
     include /etc/nginx/tls.conf;