DOC add example to reorder levels (#42935)
DOC add example to reorder levels (#42935)

* Update frame.py

Response to changes suggested on my previous pull request

* Update frame.py

Fixed the indentation issue

* Update frame.py

Built the example inside the docstring and removed the unnecessary inplace=true

* fixup

Co-authored-by: Marco Gorelli <6db2da83a2d1aabf2ecda2acf5ab66b030b8d1ef@protonmail.com>
dsm054/pandas,dsm054/pandas,rs2/pandas,dsm054/pandas,datapythonista/pandas,pandas-dev/pandas,jorisvandenbossche/pandas,pandas-dev/pandas,datapythonista/pandas,jorisvandenbossche/pandas,rs2/pandas,pandas-dev/pandas,dsm054/pandas,dsm054/pandas,rs2/pandas,jorisvandenbossche/pandas,rs2/pandas,datapythonista/pandas,jorisvandenbossche/pandas,datapythonista/pandas,pandas-dev/pandas