changelog.md: add this PR to the changelog
changelog.md: add this PR to the changelog

AngryLawyer/rust-sdl2,Cobrand/rust-sdl2,Cobrand/rust-sdl2,Cobrand/rust-sdl2,Rust-SDL2/rust-sdl2,Rust-SDL2/rust-sdl2,Rust-SDL2/rust-sdl2