DOC added example to reorder levels
Added an example for reorder levels.
Hello @Nikhil636! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:

* In the file [`pandas/core/frame.py`](https://github.com/pandas-dev/pandas/blob/9776e2e7fe6ce2b9b8d37eea63dc19abefe03268/pandas/core/frame.py):

> [Line 6840:1](https://github.com/pandas-dev/pandas/blob/9776e2e7fe6ce2b9b8d37eea63dc19abefe03268/pandas/core/frame.py#L6840): [W293](https://duckduckgo.com/?q=pep8%20W293) blank line contains whitespace
> [Line 6846:42](https://github.com/pandas-dev/pandas/blob/9776e2e7fe6ce2b9b8d37eea63dc19abefe03268/pandas/core/frame.py#L6846): [W291](https://duckduckgo.com/?q=pep8%20W291) trailing whitespace
> [Line 6851:1](https://github.com/pandas-dev/pandas/blob/9776e2e7fe6ce2b9b8d37eea63dc19abefe03268/pandas/core/frame.py#L6851): [W293](https://duckduckgo.com/?q=pep8%20W293) blank line contains whitespace
> [Line 6851:9](https://github.com/pandas-dev/pandas/blob/9776e2e7fe6ce2b9b8d37eea63dc19abefe03268/pandas/core/frame.py#L6851): [E101](https://duckduckgo.com/?q=pep8%20E101) indentation contains mixed spaces and tabs
> [Line 6851:9](https://github.com/pandas-dev/pandas/blob/9776e2e7fe6ce2b9b8d37eea63dc19abefe03268/pandas/core/frame.py#L6851): [W191](https://duckduckgo.com/?q=pep8%20W191) indentation contains tabs
> [Line 6853:26](https://github.com/pandas-dev/pandas/blob/9776e2e7fe6ce2b9b8d37eea63dc19abefe03268/pandas/core/frame.py#L6853): [W291](https://duckduckgo.com/?q=pep8%20W291) trailing whitespace
> [Line 6857:1](https://github.com/pandas-dev/pandas/blob/9776e2e7fe6ce2b9b8d37eea63dc19abefe03268/pandas/core/frame.py#L6857): [W293](https://duckduckgo.com/?q=pep8%20W293) blank line contains whitespace
> [Line 6859:1](https://github.com/pandas-dev/pandas/blob/9776e2e7fe6ce2b9b8d37eea63dc19abefe03268/pandas/core/frame.py#L6859): [W293](https://duckduckgo.com/?q=pep8%20W293) blank line contains whitespace
> [Line 6861:26](https://github.com/pandas-dev/pandas/blob/9776e2e7fe6ce2b9b8d37eea63dc19abefe03268/pandas/core/frame.py#L6861): [W291](https://duckduckgo.com/?q=pep8%20W291) trailing whitespace
> [Line 6865:1](https://github.com/pandas-dev/pandas/blob/9776e2e7fe6ce2b9b8d37eea63dc19abefe03268/pandas/core/frame.py#L6865): [W293](https://duckduckgo.com/?q=pep8%20W293) blank line contains whitespace



##### Comment last updated at 2021-08-21 07:19:08 UTC Actually, #42935 was already open for this issue, and it looks like it's still active - let's close in favour of that one for now

Next time, please check that there's not already an open PR, that one was linked in the issue

EDIT
----

This PR was a blatant attempt at plagiarising #42935  