Fix return of unshift method

Fix return of unshift method

Author: caiquecastro

book/content/part02/array.asc

@@ -73,7 +73,7 @@ Here's an example:
 [source, javascript]
 ----
 const array = [2, 5, 1];
-array.unshift(0); // ↪️ 8
+array.unshift(0); // ↪️ 4
 console.log(array); // [ 0, 2, 5, 1 ]
 array.unshift(-2, -1); // ↪️ 6
 console.log(array); // [ -2, -1, 0, 2, 5, 1 ]