Need substitute for @example

[hughjonesd]

@doctest doesn't play nice with @example path-to-R-code.R. Perhaps there should be a @doctestInclude tag to include roxygen? Or a @doctestExample to include raw R code?

[hughjonesd]

Now we have @doctestExample. Ideally we might want this to become @doctestInclude and to parse the file for more doctests.