DOC: Docstring for pandas.index.max
Checklist for the pandas documentation sprint (ignore this if you are doing
an unrelated PR):

- [X] PR title is "DOC: update the <your-function-or-method> docstring"
- [X] The validation script passes: `scripts/validate_docstrings.py <your-function-or-method>`
- [X] The PEP8 style check passes: `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [X] The html version looks good: `python doc/make.py --single <your-function-or-method>`
- [X] It has been proofread on language by another sprint participant

Please include the output of the validation script below between the "```" ticks:

```
################################################################################
######################### Docstring (pandas.Index.max) #########################
################################################################################

Return the maximum value of the object.

Return the maximum value of the object within the same type.

Returns
-------
scalar
    Maximum value.

See Also
--------
Series.max : Return the maximum value of the object.
DataFrame.max : Return the maximum value of the object.
Index.min : Return the minimum value of the object.

Examples
--------
>>> idx = pd.Index([3, 2, 1])
>>> idx.max()
3

>>> idx = pd.Index(['c', 'b', 'a'])
>>> idx.max()
'c'

################################################################################
################################## Validation ##################################
################################################################################

Docstring for "pandas.Index.max" correct. :)
```

If the validation script still gives errors, but you think there is a good reason
to deviate in this case (and there are certainly such cases), please state this
explicitly.