Rollup merge of rust-lang#74694 - GuillaumeGomez:cleanup-e0727, r=Dylan-DPC

Clean up E0727 explanation

r? @Dylan-DPC

Author: JohnTitor

src/librustc_error_codes/error_codes/E0727.md

@@ -1,6 +1,6 @@
 A `yield` clause was used in an `async` context.
 
-Example of erroneous code:
+Erroneous code example:
 
 ```compile_fail,E0727,edition2018
 #![feature(generators)]