Rollup merge of #52771 - matklad:patch-1, r=kennytm
Rollup merge of #52771 - matklad:patch-1, r=kennytm

Clarify thread::park semantics

It took me quite some time to realize that the example is not actually racy, so let's clarify it? :-)

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