Replace `style="R"` with CSS class for downstream styling support

[dieghernan]

Hi,

Would it be possible to change this line to use a class instead of a style attribute, for example:

<span class="R">R</span>

(or something similar, such as class="R-tag")

pkgdown/R/rd-html.R

Line 515 in a6abe43

as_html.tag_R <- function(x, ...) '<span style="R">R</span>'

Currently style="R" is not valid inline CSS, so it has no effect and cannot be targeted easily from custom CSS files.

Using a class would make the element properly stylable and easier to customize downstream.

Thanks!