Don't recommend ONCE_INIT in std::sync::Once
Don't recommend ONCE_INIT in std::sync::Once

ONCE_INIT is deprecated, and so suggesting it as not only being on par with, but before `Once::new` is a bad idea.
graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust