Rollup merge of #85334 - r00ster91:patch-8, r=dtolnay
Rollup merge of #85334 - r00ster91:patch-8, r=dtolnay

Add doc aliases to `unit`

I think it makes sense for `unit` to have the same doc aliases as `tuple` does.

aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust