Syntax highlighting in the README

[etiennebacher]

Minor issue but the examples in the README can be hard to read without syntax highlighting and with all the links:

Examples of dplyr are much easier to read IMO:

I think this is just a matter of replacing output: downlit::readme_document by output: github_document in README.Rmd?

[krlmlr]

Thanks, interesting. I wasn't aware that downlit kills the syntax highlighting. Need to take a closer look.

[krlmlr]

I think we're good here now, we only need to add the favicon.