Add a link to PR rapid7#4333 in the message

That way, people can see why this is if they care to.

While we have a link to the blog post at http://r-7.co/msfvenom-2015 , I
fear that by the time spring of 2015 rolls around, we'll be on a
different blogging platform and the link may be busted. I'm certain
we'll still be on GitHub then, though.

Author: Tod Beardsley

msfencode

@@ -9,6 +9,7 @@ $stderr.puts "[!] **************************************************************
 $stderr.puts "[!] *               The utility msfencode is deprecated!                   *"
 $stderr.puts "[!] *              It will be removed on or about 2015-06-08               *"
 $stderr.puts "[!] *                   Please use msfvenom instead                        *"
+$stderr.puts "[!] *  Details: https://github.com/rapid7/metasploit-framework/pull/4333   *"
 $stderr.puts "[!] ************************************************************************"
 
 msfbase = __FILE__

msfpayload

@@ -9,6 +9,7 @@ $stderr.puts "[!] **************************************************************
 $stderr.puts "[!] *               The utility msfpayload is deprecated!                  *"
 $stderr.puts "[!] *              It will be removed on or about 2015-06-08               *"
 $stderr.puts "[!] *                   Please use msfvenom instead                        *"
+$stderr.puts "[!] *  Details: https://github.com/rapid7/metasploit-framework/pull/4333   *"
 $stderr.puts "[!] ************************************************************************"
 
 msfbase = __FILE__