Clean up E0602 explanation

Author: GuillaumeGomez

src/librustc_error_codes/error_codes/E0602.md

@@ -1,9 +1,9 @@
 An unknown lint was used on the command line.
 
-Erroneous example:
+Erroneous code example:
 
 ```sh
-rustc -D bogus omse_file.rs
+rustc -D bogus rust_file.rs
 ```
 
 Maybe you just misspelled the lint name or the lint doesn't exist anymore.