NULL Handling Doc Update

[knz]

Re: NULL Handling

The following sentence:

The remaining cases are described in the next question.

Can be edited to:

The remaining cases are described in the next section.

[aniketrb-github]

Hi @Amruta-Ranade,
Can you please assign me this issue?
I would like to contribute to this issue towards the hacktoberfest event.

Thanks,
Aniket Bharsakale.

[Amruta-Ranade]

Addressed in #8521