v2.0.0

• Update NGINX to v1.20.0
• Add prefix NGINX_LE_ to variables:
  • LE_EMAIL => NGINX_LE_EMAIL
  • LE_FQDN => NGINX_LE_FQDN
  • LETSENCRYPT => NGINX_LE_LETSENCRYPT
  • TZ => NGINX_LE_TZ
  • SSL_KEY => NGINX_LE_SSL_KEY
  • SSL_CERT => NGINX_LE_SSL_CERT
  • SSL_CHAIN_CERT => NGINX_LE_SSL_CHAIN_CERT
  • PLACEHOLDER_# => NGINX_LE_PLACEHOLDER_#