Added more info about using the helper functions

README.md

@@ -169,6 +169,7 @@ Here's a little helper function for searching for a specific country's data
 
 > The helper function assumes that the JSON with the countries data is associated with a variable named `countries` which is in the same scope as the function
 
+> The helper function is to be used with the *non-combined* data sets.<br>For the *combined* data sets you can write the function yourself.
 
 ```js
 //  returns an object with the sought country's data if the search yields a result
@@ -216,6 +217,8 @@ Excerpt from the `data/countries/en/countries.php` file:
 ```
 Here's a little helper function for searching for a specific country's data
 
+> The helper function is to be used with the *non-combined* data sets.<br>For the *combined* data sets you can write the function yourself.
+
 ```php
 //  this function assumes that you have done this:
 $countries = require 'path/to/countries.php';