Hide `&mut self` methods from Deref in sidebar
Hide `&mut self` methods from Deref in sidebar

If there are no `DerefMut` impl for the type.

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