docs: Fix typos and spacing issues in Dask bag documentation

[enstenr]

This PR fixes several small documentation issues in bag.ipynb:

fixes
added missing word (“time”), ("footprint")
typo in lets -> let's
Added for more clarity-> For deeply nested data, consider flattening or using Bag first, then convert to DataFrame
user defined -> user-defined

These changes improve readability and consistency across the documentation.
No functional code has been modified.

Checklist
Updated documentation
No API changes
Notebook opens and renders as expected

[review-notebook-app]

Check out this pull request on 

See visual diffs & provide feedback on Jupyter Notebooks.

---

Powered by ReviewNB

[jacobtomlinson]

This PR strikes me as AI generated given the way the text is written in the description, especially the checklist. This is fine, but please make sure you review the diff yourself before submitting as there are a couple of clear problems where cell outputs haven't been cleared.

[enstenr]

This PR strikes me as AI generated given the way the text is written in the description, especially the checklist. This is fine, but please make sure you review the diff yourself before submitting as there are a couple of clear problems where cell outputs haven't been cleared.

sure.
The output cell i did notice in ReviewNB after creating PR, in one of my earlier PR i had similar problem where the python version was showing different. When i google, i found that it was common and will be ignored by reviewer.
So i thought this was similar to this.
Now i understood this and will take care going forward. Hopefully now i have done it in correct way.

checklist - I provided gpt on what all i did and it formatted and gave in better phrase.

[jacobtomlinson]

Looks good thanks