Fix some typos
Fix some typos

Signed-off-by: Yuki Okushi <0a792b09e3c7d426e6dc7b64bc4e95f557d97c14@2k36.org>

rust-lang/rustc-dev-guide,rust-lang/rustc-dev-guide,rust-lang/rustc-dev-guide,rust-lang/rustc-dev-guide