add reminder for proxy remote_addr

etc/snippets_subdomain.conf

@@ -8,6 +8,10 @@ index index.php index.html;
 root /var/www/dotclear/app;
 client_max_body_size 32m;
 
+# Fix remote_addr, uncomment these lines and set proxy IP or subnet
+#real_ip_header    X-Forwarded-For;
+#set_real_ip_from  x.x.x.x/x;
+
 # Blogs public paths
 location ~ /public {
     root /var/www/dotclear/blogs;