Clean up E0761 explanation

src/librustc_error_codes/error_codes/E0761.md

@@ -2,24 +2,20 @@ Multiple candidate files were found for an out-of-line module.
 
 Erroneous code example:
 
-```rust
+```ignore (multiple source files required for compile_fail)
 // file: ambiguous_module/mod.rs
 
 fn foo() {}
-```
 
-```rust
 // file: ambiguous_module.rs
 
 fn foo() {}
-```
 
-```ignore (multiple source files required for compile_fail)
+// file: lib.rs
+
 mod ambiguous_module; // error: file for module `ambiguous_module`
                       // found at both ambiguous_module.rs and
                       // ambiguous_module.rs/mod.rs
-
-fn main() {}
 ```
 
 Please remove this ambiguity by deleting/renaming one of the candidate files.