Rollup merge of #44854 - lucasem:atomic-docs, r=steveklabnik
Rollup merge of #44854 - lucasem:atomic-docs, r=steveklabnik

docs improvement sync::atomic::Atomic*

Addresses the `Atomic*` part of #29377.
r? @steveklabnik

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