Solve some Docker Setup scaling issues (#1561)

deployment/docker/nginx.conf

@@ -4,7 +4,7 @@ pid /var/run/nginx.pid;
 daemon off;
 
 events {
-	worker_connections 768;
+	worker_connections 4096;
 }
 
 http {
@@ -39,7 +39,7 @@ http {
 	include /etc/nginx/conf.d/*.conf;
 
     server {
-        listen 80 default_server;
+        listen 80 backlog=4096 default_server;
         listen [::]:80 ipv6only=on default_server;
         server_name _;
         index index.php index.html;

doc/admin/installation/docker_smallscale.rst

@@ -182,6 +182,7 @@ named ``/etc/systemd/system/pretix.service`` with the following content::
         -v /var/pretix-data:/data \
         -v /etc/pretix:/etc/pretix \
         -v /var/run/redis:/var/run/redis \
+        --sysctl net.core.somaxconn=4096
         pretix/standalone:stable all
     ExecStop=/usr/bin/docker stop %n