Adding a dark-mode to HTML vignettes

[grimbough]

Hi @aoles

At the moment there seems to be quite some effort in the R community towards improving accessibility of websites, documentation, etc. We've already made some enhancements to BiocStyle in #91 but there's probably a lot else to consider.

The R Forwards team have made some suggestions at rstats-gsod/gsod2022#5 and there's an ongoing effort led by @lwaldron to convert some of the existing Bioconductor Rnw -> PDF vignettes into Rmd -> HTML (https://trello.com/b/nJHqzR1j/bioconductor-vignettes-rnw-rmd-project).

I was wondering if you'd be open to the idea of a 'dark-mode' style sheet added to the package, with the option for a user to toggle between the two modes (or selection based detection of operating system preferences). This seems like a pretty common option on a lot of websites now and I'm happy to spend some time on it if it's something you think the package might benefit from.