Need to update documents about 'define-output' and 'include-output' commands are not working by default.

[yukitos]

@tpetricek taught me the reason and there's no documents about it on twitter. I think we need to provide the way to enable it (or at least add description to enable it).

[stevenranney]

@yukitos So, how is this enabled?

Thanks for opening the issue and for pinging @tpetricek on Twitter.

[tpetricek]

You need to create FsiEvaluator. Check out the demo here: https://github.com/TahaHachana/XPlot/blob/master/docs/tools/generate.fsx#L78.

This also creates a couple of transformations for rendering of XPlot charts in the docs: https://github.com/TahaHachana/XPlot/blob/master/docs/tools/formatters.fsx