Improve scale_(x|y)_continuous documentation

[paleolimbot]

There are several opportunities to improve the documentation for scale_(x|y)_continuous(). This is a documentation issue intended for the tidyverse dev day (#3267).

• The current parameter documentation for oob describes scales::censor, which may be worth linking to. scales::squish and scales::squish_infinite can be used here as well, which is not obvious from either the ggplot2 or scales documentation.

• The parameter documentation for sec.axis in scale_continuous should link to sec_axis() (and possibly be removed from the "see also" section).

• The links to scales::rescale() aren't active on the site, and it isn't obvious that rescale() isn't a function in ggplot2 (from several scale-related documentation pages).

[lock]

This old issue has been automatically locked. If you believe you have found a related problem, please file a new issue (with reprex) and link to this issue. https://reprex.tidyverse.org/