Document the sendResult() function

[zbynekstara]

The sendResult() function is used in the example app (https://github.com/darryncampbell/plugin-intent-api-exerciser/blob/master/www/js/index.js), but is not documented in the readme file. The example is taken from the sample app.

[darryncampbell]

Thank you for the contribution, merging...

[zbynekstara]

@darryncampbell When sendResult is called with no arguments or only with one object, Cordova throws the following error:

jQuery.Deferred exception: Wrong type for parameter "callback" of IntentShim.sendResult: Expected Function, but got Undefined. TypeError: Wrong type for parameter "callback" of IntentShim.sendResult: Expected Function, but got Undefined.
        at Object.checkArgs
        at IntentShim.sendResult
        ...

I wasn't too sure what the callback argument was for, so I didn't include it in the example, but now I realize that if someone copy-pastes the sample code, their program will not run. Should I make a new PR with an empty function in the example and mention that both arguments need to be provided? Like this:

window.plugins.intentShim.sendResult(
    {
        extras: {
            'Test Intent': 'Successfully sent',
            'Test Intent int': 42,
            'Test Intent bool': true,
            'Test Intent double': parseFloat("142.12")
        }
    },
    function() {

    }
);