Fixed typo "but the tests are expects"

exercises/hello-world/GETTING_STARTED.md

 
 ## Step 2
 
-Run the tests again. It will give you a new error, since now the method exists, but the tests are expects the
+Run the tests again. It will give you a new error, since now the method exists, but the tests expect the
 method to accept one argument as input, a name.
 
 The errors will look something like: