Minor fix - Iterator pattern example

Author: kamranahmedse

README.md

@@ -1414,16 +1414,16 @@ And then it can be used as
 ```php
 $stationList = new StationList();
 
-$stationList->addStation(new Station(89));
-$stationList->addStation(new Station(101));
-$stationList->addStation(new Station(102));
-$stationList->addStation(new Station(103.2));
+$stationList->addStation(new RadioStation(89));
+$stationList->addStation(new RadioStation(101));
+$stationList->addStation(new RadioStation(102));
+$stationList->addStation(new RadioStation(103.2));
 
 foreach($stationList as $station) {
     echo $station->getFrequency() . PHP_EOL;
 }
 
-$stationList->removeStation(new Station(89)); // Will remove station 89
+$stationList->removeStation(new RadioStation(89)); // Will remove station 89
 ```
 
 👽 Mediator