DOC: Add none as a default argument for orient
- [x] closes #48252 

Add None as an acceptable argument for orient in read_json over [here](https://pandas.pydata.org/docs/reference/api/pandas.read_json.html)

Based on my understanding, None does nothing. It is just an acceptable value. 
The value of 'orient' depends on the value of "typ" parameter as mentioned later in the docstring over [here](https://pandas.pydata.org/docs/reference/api/pandas.read_json.html):

> The allowed and default values depend on the value of the typ parameter.

> For Series: default is index and For Frame: default is columns

Since, it is already mentioned, I am not quite sure how shall I improve it. Shall I change the default value of it being 'columns' instead of None since the default value of 'typ' is 'Series'? thx @ambujpawar 