Rollup merge of #49170 - steveklabnik:gh49127, r=nagisa
Rollup merge of #49170 - steveklabnik:gh49127, r=nagisa

Clarify AcqRel's docs

This implied things that are not true.

Fixes #49127

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