Rollup merge of #59889 - andrewbanchich:minor-text-fixes, r=estebank
Rollup merge of #59889 - andrewbanchich:minor-text-fixes, r=estebank

Update diagnostics.rs

Add `a` and other minor text improvements

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