documentation: update documentation following node-sass-chokidar updates

Created by: eMerzh

Hi,

since first node-sass-chokidar 1.1.0 , the watch command also do an initial compile (unless you ask it not to ;) )

so i've update the doc accordingly

Ref: https://github.com/michaelwayman/node-sass-chokidar/blob/master/CHANGELOG.md#110