better checking for SSL servers, even though it probably doesn't fix the cookie bug

doc/install/sample-nginx.conf

@@ -59,6 +59,8 @@ server {
   ssl_ciphers ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv3:+EXP;
   ssl_prefer_server_ciphers on;
 
+  fastcgi_param HTTPS on;
+
   index index.php;
   charset utf-8;
   root /var/www/red;