web: split TLS configuration and make it stronger

Resources:

- https://hynek.me/articles/hardening-your-web-servers-ssl-ciphers/
- https://weakdh.org/sysadmin.html

web/rootfs/defaults/default

@@ -2,11 +2,10 @@ server {
 	listen 80 default_server;
 	listen 443 ssl;
 
-	ssl_certificate /config/keys/cert.crt;
-	ssl_certificate_key /config/keys/cert.key;
-
 	server_name _;
 
+	include /config/nginx/ssl.conf;
+
 	client_max_body_size 0;
 
 	root /usr/share/jitsi-meet;