minor doc tweak

[petethomas]

Original example was throwing an error:

node.js:201
        throw e; // process.nextTick error, or 'error' event on first tick
              ^
TypeError: Cannot read property 'hello' of undefined
    at Object.<anonymous> (/home/pete/ctest.js:31:2)
    at Module._compile (module.js:441:26)
    at Object..js (module.js:459:10)
    at Module.load (module.js:348:31)
    at Function._load (module.js:308:12)
    at Array.0 (module.js:479:10)
    at EventEmitter._tickCallback (node.js:192:40)

[doug-martin]

fixed in proxy.js jsdoc comment, will republish