Clean up E0076 long explanation

Author: GuillaumeGomez

src/librustc_error_codes/error_codes/E0076.md

@@ -1,21 +1,24 @@
-When using the `#[simd]` attribute to automatically use SIMD operations in tuple
-struct, the types in the struct must all be of the same type, or the compiler
-will trigger this error.
+All types in a tuple struct aren't the same when using the `#[simd]`
+attribute.
 
-This will cause an error:
+Erroneous code example:
 
 ```compile_fail,E0076
 #![feature(repr_simd)]
 
 #[repr(simd)]
-struct Bad(u16, u32, u32);
+struct Bad(u16, u32, u32); // error!
 ```
 
-This will not:
+When using the `#[simd]` attribute to automatically use SIMD operations in tuple
+struct, the types in the struct must all be of the same type, or the compiler
+will trigger this error.
+
+Fixed example:
 
 ```
 #![feature(repr_simd)]
 
 #[repr(simd)]
-struct Good(u32, u32, u32);
+struct Good(u32, u32, u32); // ok!
 ```