dt.month_name doesn't return the name of the month
I'm trying to get the name of the month of the year based on my datatime variable `created_data` in my dataframe `df_noise`, and tried:

`df_noise['month'] = df_noise.created_date.dt.month_name`

and pandas returns the following in every row of the column

`<bound method PandasDelegate._add_delegate_accessors.<locals>._create_delegator_method.<locals>.f of <pandas.core.indexes.accessors.DatetimeProperties object at 0x0000011D017F9630>>
`

If I use 

`df_noise['month'] = df_noise.created_date.dt.month`

pandas will return the numerical values of the month. 

Am I missing somthing? Is there a way to get the name of the month? The [doc ](https://pandas.pydata.org/pandas-docs/stable/generated/pandas.Series.dt.month_name.html) here doesn't have examples.

verison: 
`'0.23.4'`