Added missing types for range

Author: David Barda

en/02.3.md

@@ -105,7 +105,7 @@ There are two important operations in loops which are `break` and `continue`. `b
 	// break prints 10、9、8、7、6
 	// continue prints 10、9、8、7、6、4、3、2、1
 ```	
-`for` can read data from `slice` and `map` when it is used together with `range`.
+`for` can read data from `array`, `slice`, `map` and `string` when it is used together with `range`.
 ```Go
 	for k,v:=range map {
     	fmt.Println("map's key:",k)