Added an example where explicitly dropping a lock is necessary/a good idea.
Added an example where explicitly dropping a lock is necessary/a good idea.

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