DOC: fix typo in `DataFrame.plot.hist` docstring
Spot a rendering issue [here](https://pandas.pydata.org/docs/dev/reference/api/pandas.DataFrame.plot.hist.html)
![hist](https://github.com/pandas-dev/pandas/assets/47032563/16f57912-de5d-4d21-aaa5-4d3671d1cb90)

Thanks @yuanx749 