Rollup merge of #40987 - maccoda:convert-docs, r=steveklabnik
Rollup merge of #40987 - maccoda:convert-docs, r=steveklabnik

API docs: Convert

Clean up of the convert module documentation following points in #29349

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