Added example to the aggregate function
Added example of k-hot encoding to the aggregate function

- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Hello @XtremeGood! 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/1e08bee60bbefc18f37c1ced2ab595ed4dd2d832/pandas/core/frame.py):

> [Line 7496:5](https://github.com/pandas-dev/pandas/blob/1e08bee60bbefc18f37c1ced2ab595ed4dd2d832/pandas/core/frame.py#L7496): [E101](https://duckduckgo.com/?q=pep8%20E101) indentation contains mixed spaces and tabs
> [Line 7496:5](https://github.com/pandas-dev/pandas/blob/1e08bee60bbefc18f37c1ced2ab595ed4dd2d832/pandas/core/frame.py#L7496): [W191](https://duckduckgo.com/?q=pep8%20W191) indentation contains tabs
> [Line 7504:89](https://github.com/pandas-dev/pandas/blob/1e08bee60bbefc18f37c1ced2ab595ed4dd2d832/pandas/core/frame.py#L7504): [E501](https://duckduckgo.com/?q=pep8%20E501) line too long (106 > 88 characters)
> [Line 7511:56](https://github.com/pandas-dev/pandas/blob/1e08bee60bbefc18f37c1ced2ab595ed4dd2d832/pandas/core/frame.py#L7511): [W291](https://duckduckgo.com/?q=pep8%20W291) trailing whitespace
> [Line 7512:89](https://github.com/pandas-dev/pandas/blob/1e08bee60bbefc18f37c1ced2ab595ed4dd2d832/pandas/core/frame.py#L7512): [E501](https://duckduckgo.com/?q=pep8%20E501) line too long (101 > 88 characters)
> [Line 7518:31](https://github.com/pandas-dev/pandas/blob/1e08bee60bbefc18f37c1ced2ab595ed4dd2d832/pandas/core/frame.py#L7518): [W291](https://duckduckgo.com/?q=pep8%20W291) trailing whitespace



##### Comment last updated at 2020-10-31 21:24:13 UTC > 
> 
> As noted in the issue I'm -1 on putting this in

No problems. I will find a real `Good First Coding` issue. 