removed erroneous tip

I'm working through the tutorial myself and got to this point.

Don’t forget to add a require_once call for this class to the bootstrap.php

This advice is wrong. The class is located in the src directory and so is autoloaded when required. No require statement is necessary.

docs/en/tutorials/getting-started.rst

@@ -1473,8 +1473,6 @@ the previously discussed query functionality in it:
         }
     }
 
-Don't forget to add a `require_once` call for this class to the bootstrap.php
-
 To be able to use this query logic through ``$this->getEntityManager()->getRepository('Bug')``
 we have to adjust the metadata slightly.