ssl_trusted_certificate should point to chain.pem if we're demonstrating LetsEncrypt: https://community.letsencrypt.org/t/howto-ocsp-stapling-for-nginx/13611/5
ssl_trusted_certificate should point to chain.pem if we're demonstrating LetsEncrypt: https://community.letsencrypt.org/t/howto-ocsp-stapling-for-nginx/13611/5