Update compiler/rustc_error_codes/src/error_codes/E0549.md
Update compiler/rustc_error_codes/src/error_codes/E0549.md

Co-authored-by: Guillaume Gomez <b1db332606efda9d9987ee09ce352e2a96143e72@gmail.com>
aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust