DOC: Fix formatting for Raises section

This needs Examples, too.  I think it's used like this?

```
cdist([(0, 0), (1, 1)], [(0, 1), (0, 2), (3, 0), (1, 1)])
Out[190]: 
array([[ 1.    ,  2.    ,  3.    ,  1.4142],
       [ 1.    ,  1.4142,  2.2361,  0.    ]])
```