In bot.js, comments mention that the step is a WaterfallStep, not a WaterfallStepContext.

[cmayomsft]

For example, in promptForMenu.

Doesn't much matter in JS since it's untyped, but would be helpful if users of the sample are directed to the correct class to learn more.

All the dialog/prompt methods have this same issue.

@param step Waterfall dialog step