Examples in MultiIndex.rename documentation do not call the function
#### Code Sample

In Pandas version 0.20, The [documentation for the function `pandas.MultiIndex.rename`](https://pandas.pydata.org/pandas-docs/stable/generated/pandas.MultiIndex.rename.html) includes an "Examples" section with five lines of Python code.  

Here are the examples:
```
>>> Index([1, 2, 3, 4]).set_names('foo')
Int64Index([1, 2, 3, 4], dtype='int64')
>>> Index([1, 2, 3, 4]).set_names(['foo'])
Int64Index([1, 2, 3, 4], dtype='int64')
>>> idx = MultiIndex.from_tuples([(1, u'one'), (1, u'two'),
                                  (2, u'one'), (2, u'two')],
                                  names=['foo', 'bar'])
>>> idx.set_names(['baz', 'quz'])
MultiIndex(levels=[[1, 2], [u'one', u'two']],
           labels=[[0, 0, 1, 1], [0, 1, 0, 1]],
           names=[u'baz', u'quz'])
>>> idx.set_names('baz', level=0)
MultiIndex(levels=[[1, 2], [u'one', u'two']],
           labels=[[0, 0, 1, 1], [0, 1, 0, 1]],
           names=[u'baz', u'bar'])
```

#### Problem description

The examples do not call the `MultiIndex.rename` function.  Expected contents of the documentation:  the examples given for the `rename` function should actually call the `rename` function.

#### Output of ``pd.show_versions()``

N/A, documentation bug.

#### Meta note
The link above will begin pointing at documentation for a *different version* of Pandas once the successor to version 0.20 is released as a stable version.  Unfortunately, there is no link to version 0.20 documentation per se on the [pandas homepage](https://pandas.pydata.org/).

