Additional use of test statement

A suggestion to improve documentation. Regarding the "test": statement which may be employed in the definition of client
classes. There are no examples in the ARM that document usage where two separate
values retrieved from a packet are compared with each other. All examples compare
a value retrieved from a packet with a constant value or test for membership of
other classes. The following is also possible:

"client-classes": [
 { "name": "Infrastructure",
        "test": "option[82].option[2].hex == pkt4.mac" },
   ...
],

This is a result of discussions done in RT#21407