Code sample in pandas/core/categorical.py 
The code sample in pandas/core/categorical.py needs a minor correction. In https://github.com/pydata/pandas/blob/master/pandas/core/categorical.py#L186:

```
>>> a = Categorical(['a','b','c','a','b','c'], ['c', 'b', 'a'])
>>> a.min()

```

Shouldn't a.is_ordered() come before a.min() ?
