Auto merge of #32529 - Manishearth:concurrency-fx, r=steveklabnik
Auto merge of #32529 - Manishearth:concurrency-fx, r=steveklabnik

Improve concurrency chapter

Incorporate feedback from HN

r? @steveklabnik

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