Add ranking comment

Author: jvazquez-r7

modules/exploits/linux/http/multi_ncc_ping_exec.rb

@@ -6,7 +6,7 @@
 require 'msf/core'
 
 class Metasploit3 < Msf::Exploit::Remote
-  Rank = NormalRanking
+  Rank = NormalRanking # Only tested on Emulated environment
 
   include Msf::Exploit::Remote::HttpClient
   include Msf::Exploit::Remote::HttpServer::HTML