Rollup merge of #38587 - GuillaumeGomez:arc_docs, r=frewsxcv
Rollup merge of #38587 - GuillaumeGomez:arc_docs, r=frewsxcv

Add missing urls in Arc docs

r? @frewsxcv

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