Elide lifetimes in DerefMut documentation
Elide lifetimes in DerefMut documentation

 - Elide lifetimes to increase the readability
   of `DerefMut` examples

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