Rollup merge of rust-lang#72976 - GuillaumeGomez:cleanup-e0642, r=Dyl…

…an-DPC

Clean up E0642 explanation

r? @Dylan-DPC

src/librustc_error_codes/error_codes/E0642.md

@@ -1,6 +1,6 @@
 Trait methods currently cannot take patterns as arguments.
 
-Example of erroneous code:
+Erroneous code example:
 
 ```compile_fail,E0642
 trait Foo {