rewrite comment on how to get closure sig, per arielb1's suggestion
rewrite comment on how to get closure sig, per arielb1's suggestion

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