fix(map.jinja): use upstream default for `worker_connections`

* Close #261
* https://nginx.org/en/docs/ngx_core_module.html#worker_connections

nginx/map.jinja

@@ -130,7 +130,7 @@
         'config': {
             'worker_processes': 'auto',
             'events': {
-                'worker_connections': 768,
+                'worker_connections': 512,
             },
             'http': {
                 'sendfile': 'on',