Show methods implemented by loaded packages more prominently

[krlmlr]

Example: if dbplyr is loaded, ?mutate would contain a link to ?dbplyr::mutate.tbl_lazy .

Pretty much like DBI, e.g., https://dbi.r-dbi.org/reference/dbConnect.html .

Relevant for tidyverse/duckplyr#214 and of course the existing backends.

CC @maelle.

[krlmlr]

Oh, it's at the very bottom, in the "Methods" section. Should this information be part of the description instead (first section)?