Review/rewrite support for non-standard links

[maurolepore]

Standard links look like this: https://owner.github.io/repo/..., e.g.:

https://forestgeo.github.io/fgeo.tool/reference/read_vft.html

Non-standard links look like this: https://custom-stuff/..., e.g.:

https://dplyr.tidyverse.org/reference/filter.html