Input file paths are wrong

For[ Exercise: Machine Learning Competitions](https://github.com/Kaggle/learntools/blob/9dae309d167fceb0cd9eb29ed6e625acb52e0af7/notebooks/machine_learning/raw/ex7.ipynb), the train data file path should be
```iowa_file_path = '../input/train.csv'```

The current path is not working:
```iowa_file_path = '../input/home-data-for-ml-course/train.csv'```

Not making a PR because I'm not sure if the path should be corrected or the files should be placed in that path.