Styling when used with kableExtra

[dmurdoch]

In this issue: haozhu233/kableExtra#849 , @g-antonello wants to use kableExtra::kbl() with BiocStyle::html_document output. There are two issues:

• kableExtra::kbl() ignores the tab.cap chunk option. That's easy to work around.
• It also defaults to a style quite different from the default style produced by knitr::kable() when run in BiocStyle::html_document. I don't know if there's a workaround for that or if one or both packages needs to change.