puppet: Increase worker_processes to optimize for prod0.

(imported from commit 35c7443c6ac3f8286ada4a7baf3655559176536e)

puppet/zulip/files/nginx/nginx.conf

@@ -1,6 +1,8 @@
 user zulip;
 
-worker_processes 4;
+# This is set to 8 because that's how many processors we have on
+# prod0.  On other systems, it's more than we strictly need.
+worker_processes 8;
 pid /var/run/nginx.pid;
 
 events {