Auto merge of #30332 - bluss:nomicon-variance, r=gankro
Auto merge of #30332 - bluss:nomicon-variance, r=gankro

Update nomicon for variance typo & contravariance

Fixes #28704
Fixes #28100

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