uitleg voor installeren ssl certificaat via certbot:
https://www.strato.nl/blog/lets-encrypt-gratis-ssl-certificaat-voor-servers/
https://certbot.eff.org/instructions?ws=nginx&os=pip
https://medium.com/@TechInWire/using-letsencrypt-to-secure-multiple-domains-with-nginx-95427c54be95
https://www.digitalocean.com/community/tutorials/how-to-secure-nginx-with-let-s-encrypt-on-ubuntu-16-04
sudo certbot --nginx -d example.com -d www.example.com
