deprecated parameters are listed as a function deprecation in the reference index

[jayhesselberth]

The recommended way to deprecate a parameter is to add a lifecycle badge the Rd parameter.

New changes in pkgdown pick this up and add the deprecation into the reference index, even if the function itself is not, which looks a little odd and is misleading (i.e., only the parameter is deprecated, not the function).

[hadley]

Ooops, I should restrict my search for figures to just the description, not the entire Rd.

[jayhesselberth]

or alternatively pick up param lifecycle markup separately and list by the param on the rendered Rd page.

[hadley]

@jayhesselberth yeah, that would be nice, but that's going to be a lot more work, and I'd like to see what the reaction to the function-level lifecycle labelling is first.