Fix doc comment on MaybeUninit::drop.
Fix doc comment on MaybeUninit::drop.

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