update README for JavaScript

code/JavaScript/Arrays/forEach.js

@@ -0,0 +1,9 @@
+// arr.forEach(function callback(currentValue, index, array) {
+  // your iterator
+// }[, thisArg]);
+
+Синтаксис
+
+arr.forEach(function callback(currentValue, index, array) {
+  //your iterator
+}[, thisArg]);