Watch - flush

[skirtles-code]

The flush option for watch is documented elsewhere but it isn't mentioned in API Reference / Options / Data / watch.

e.g.:

watch: {
  a: {
    flush: 'sync',
    handler () {/**/}
  }
}

In addition, I think it would be preferable to have handler, immediate, deep and flush listed explicitly as options rather than relying on the example. deep and immediate are explained in much greater detail under $watch, which I find a little odd as that is a less common way to use watchers and I doubt anyone using watch will think to look under $watch.

$watch also needs flush documenting.