Rollup merge of #70309 - GuillaumeGomez:cleanup-e0452, r=Dylan-DPC

Clean up E0452 explanation

r? @Dylan-DPC

Author: Centril

src/librustc_error_codes/error_codes/E0452.md

@@ -1,4 +1,6 @@
-An invalid lint attribute has been given. Erroneous code example:
+An invalid lint attribute has been given.
+
+Erroneous code example:
 
 ```compile_fail,E0452
 #![allow(foo = "")] // error: malformed lint attribute