Refactor changes

Author: Polkaverse

src/librustc_error_codes/error_codes/E0703.md

@@ -4,7 +4,6 @@ Erroneous code example:
 
 ```compile_fail,E0703
 extern "invalid" fn foo() {} // error!
-
 # fn main() {}
 ```
 
@@ -14,6 +13,5 @@ replace the given ABI from 'Rust'.
 
 ```
 extern "Rust" fn foo() {} // ok!
-
 # fn main() { }
 ```