Update guide_dataset.rst

[varunity]

Correcting a typo. No tests or extra documentation needed.

fixes [org/repo/issue#]

• Test coverage exists
• Documentation exists

QA Steps

• Read the edited sentence, see if it makes more sense.

[dafeder]

Hi @varunity! 👋🏽 I think "distribution" is technically correct here but I agree "file" is too, and is clearer. Thanks for the PR, will merge once we have this one flaky test passing again.