[master] relay -> relay4 in classify doc

doc/guide/classify.xml

@@ -166,8 +166,8 @@
 <row><entry>Option Hex</entry><entry>option[code].hex</entry><entry>The value of the option with code "code" from the packet as hex</entry></row>
 <row><entry>Option Exist</entry><entry>option[code].exist</entry><entry>If the option with code "code" is present in the packet "true" else "false"</entry></row>
 <row><entry>DHCPv4 Relay Agent
-sub-option</entry><entry>relay[code].hex</entry><entry>The value of
-sub-option with code "code" from the Relay Agent Information option
+sub-option</entry><entry>relay4[code].hex</entry><entry>The value of
+sub-option with code "code" from the DHCPv4 Relay Agent Information option
 (option 82)</entry></row>
           </tbody>
           </tgroup>
@@ -195,8 +195,8 @@ sub-option with code "code" from the Relay Agent Information option
       </para>
 
       <para>
-        "relay[code].hex" attempts to extract the value of the sub-option
-        "code" from the option inserted as the Relay Agent Information
+        "relay4[code].hex" attempts to extract the value of the sub-option
+        "code" from the option inserted as the DHCPv4 Relay Agent Information
         (82) option. If the packet doesn't contain a RAI option, or the RAI
         option doesn't contain the requested sub-option, the expression returns
         an empty string. The string is presented as a byte string of the