Error documentation 'Time Cartesian Axis'

[M0untainfox]

Hello,

it seems to be an error in the following page: Time Cartesian Axis.

I use Chart.js 2.6.0 and 'unitStepSize' has no effect on my axis scale, Instead of 'unitStepSize' should use 'StepSize' and that work fine.

Thanks for your works and that lib

[etimberg]

Thanks for reporting this. I'm happy to merge a PR fixing this