Keep consistency in example for Stdin StdinLock
Keep consistency in example for Stdin StdinLock

Stdin uses handle whereas StdinLock uses stdin_lock, changed it to handle.
aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust