Update src/librustc_error_codes/error_codes/E0634.md
Update src/librustc_error_codes/error_codes/E0634.md

Co-Authored-By: Dylan DPC <746acce186260efad9cee682d6316e27a5faba1c@gmail.com>
aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust