DOC: Fixing EX01 - Added example
- [ x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).

Towards https://github.com/pandas-dev/pandas/issues/37875

~~Modified `validate_docstrings.py`: it was raising for "importing pandas". If I didn't import pandas_gbq on the docstring, the error was for undeclared name.~~

~~Not sure if I have to add a test for that case or if the fix is good enough.~~

Looks good. Could you merge main once more? It looks green if someone very kind wants to merge, it would be great. 
 Thanks @DeaMariaLeon 