use similar syntax in all arms

Fixes #17672

src/doc/guide.md

@@ -2030,7 +2030,7 @@ fn main() {
     match cmp(input, secret_number) {
         Less    => println!("Too small!"),
         Greater => println!("Too big!"),
-        Equal   => { println!("You win!"); },
+        Equal   => println!("You win!"),
     }
 }