[guide] fix arrow IIFE call

Currently, it throws.

README.md

@@ -2546,10 +2546,10 @@ Other Style Guides
     }());
 
     // good, but legacy (guards against the function becoming an argument when two files with IIFEs are concatenated)
-    ;(() => {
+    ;((() => {
       const name = 'Skywalker';
       return name;
-    }());
+    })());
     ```
 
     [Read more](https://stackoverflow.com/questions/7365172/semicolon-before-self-invoking-function/7365214%237365214).