Rollup merge of #55047 - tshepang:simple, r=alexcrichton
Rollup merge of #55047 - tshepang:simple, r=alexcrichton

doc: make core::fmt::Error example more simple

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