Just upgraded to RStudio 1.1 (Mac OS 10.12.6, R 3.4.0), and it looks like all of the hyperlinks in the help documentation is colored white. What gives?
What editor theme are you using? Does the issue persist after closing and restarting RStudio? Does switching the editor theme alleviate the issue?
Bingo! There appear to be some weird interactions between the RStudio Theme and the Editor Theme. For example, I was using the "Classic" RStudio theme (primarily dark on light) along with the "Material" editor theme (primarily light on dark). My guess is that Material specifies a white hyperlink color, which the help docs were picking up.
These types of interactions are unexpected, and I would encourage the RStudio team to look into how the Editor themes impact panels beyond the script editor.