DOC: fill in class names for rename methods
The documentation for the `inplace` parameter has the `%(klass)` placeholder from the original NDFrame. This fills in the appropriate values in the following places:

* http://pandas.pydata.org/pandas-docs/version/0.23/generated/pandas.DataFrame.rename.html
* http://pandas.pydata.org/pandas-docs/version/0.23/generated/pandas.Series.rename.html
thanks!