Rollup merge of #45376 - topecongiro:fix-typos-in-readme, r=Mark-Simulacrum
Rollup merge of #45376 - topecongiro:fix-typos-in-readme, r=Mark-Simulacrum

Fix typos in src/librustc/README.md

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