clarified description of join method.

line 203 instead of: An array of strings can be flattened to a single string...
                     An array can be flattened to a single string...

Author: keithGrout

04_data.txt

@@ -200,8 +200,8 @@ console.log(mack);
 (((Array type)))(((array,methods)))(((push method)))(((pop
 method)))(((join method)))The `push` method can be used to add values
 to the end of an array. The `pop` method does the opposite. It removes
-the value at the end of the array and returns it. An array of strings
-can be flattened to a single string with the `join` method. The
+the value at the end of the array and returns it. An array can be 
+flattened to a single string with the `join` method. The
 argument given to `join` determines the text that is glued between the
 array's elements.