"rasa init" doesn't ask if user wants to train a model

**Rasa version**: Rasa 1.6.0a1

**Python version**: Python 3.7.4

**Operating system**: macOs Catalina 

**Issue**:

According to the docs "rasa init" should ask user if the model has to be trained, in fact that doesn't happen and the model is trained anyway.

**Command or request that led to error**:
```
rasa init
```