update ssl_ciphers

[Original source](https://raymii.org/s/tutorials/Strong_SSL_Security_On_nginx.html) changed ciphers in https://github.com/RaymiiOrg/ingsoc-html/commit/fb5f7ff7ac7e434fc59922918e18712623d3c050. Also recommended from https://wiki.mozilla.org/Security/Server_Side_TLS.