Change to my nginx config that seemed to help my lemmy and lotide installs

So both lemmy and lotide were having big problems where they'd get totally overwhelmed, especially once I started federating with huge instances. At first I thought it was because my servers aren't very powerful, but eventually I got the idea that maybe it's because it can't keep up with federation data from the big instances.

So I decided to limit the connections per IP address. Long-term testing isn't done yet, but so far both my lemmy and lotide instances aren't getting crushed when they're exposed to the outside world, so I think it's helping.

In /etc/nginx/nginx.conf, under the http section, I added the line "limit_conn_zone $binary_remote_addr zone=conn_limit_per_ip:10m;"

Then, in my sites-available folder for the services, I added "limit_conn conn_limit_per_ip 4;" or something similar. Both lemmy and lotide have different sections for ActivityPub and API, so it appears I can limit the connections just to those parts of the site.

It's only been a few days, but whereas before both instances would die randomly pretty quickly once exposed to the outside world, now it appears that they're both stable. Meanwhile, I'm still getting federated posts and comments.