Modified a path in docs.

docs/exercise2.rst

@@ -23,7 +23,7 @@ Problem 2.1
 
 Change to folder **exercises/work/2_data_flow**. Copy the provided template 
 **exercises/inputs/2_data_flow/template.[json|yaml]** and complete it so that 
-the script **exercises/problems/recruiting-script.py** is implemented as a 
+the script **exercises/problems/2_data_flow/recruiting-script.py** is implemented as a 
 workflow. Check the workflow, add it to LaunchPad and run it in *singleshot* mode 
 watching the changes in the Fireworks with the workflow run.