Review use of links within pkgdown site

[alice-hannah]

E.g. links to 'Colour scales' section of reference index.

• Absolute links to other pages of pkgdown site do not account for dev version of site
• Relative links (e.g. ../reference/) work within dev version of site but won't work from help docs in R studio or GitHub

Is this relevant? https://pkgdown.r-lib.org/reference/autolink_html.html