Adds ssl stronger settings to default nginx config.

doc/debian/jitsi-meet/jitsi-meet.example

     listen 443 ssl;
     server_name jitsi-meet.example.com;
 
+    ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
+    ssl_prefer_server_ciphers on;
+    ssl_ciphers "EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA256:EECDH+aRSA+SHA256:EECDH+ECDSA+SHA384:EECDH+ECDSA+SHA256:EECDH+aRSA+SHA384:EDH+aRSA+AESGCM:EDH+aRSA+SHA256:EDH+aRSA:EECDH:!aNULL:!eNULL:!MEDIUM:!LOW:!3DES:!MD5:!EXP:!PSK:!SRP:!DSS:!RC4:!SEED";
+
+    add_header Strict-Transport-Security "max-age=31536000";
+
     ssl_certificate /var/lib/prosody/jitsi-meet.example.com.crt;
     ssl_certificate_key /var/lib/prosody/jitsi-meet.example.com.key;