Refactor code

src/librustc_error_codes/error_codes/E0703.md

@@ -6,7 +6,6 @@ Erroneous code example:
 extern "invalid" fn foo() {} //~ ERROR
 
 fn main() { }
-
 ```
 At present there the few predefined ABI's (like Rust, C, system, etc.)
 which we can use in our Rust code. Please verify the ABI from the

src/test/ui/parser/issue-8537.stderr

@@ -8,3 +8,4 @@ LL |   "invalid-ab_isize"
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0703`.