Add documentation for .ipynb_checkpoints directory

[sanaa-shaik]

References

Closes #6659

Summary

This PR adds documentation explaining the '.ipynb_checkpoints' directory in Jupyter Notebook.

Details

• Explains what the directory is
• Describes why it exists and how it works
• Mentions its role in storing checkpoint (backup) notebooks
• Clarifies that it can be deleted and will be recreated

Motivation

This helps reduce user confusion about the '.ipynb_checkpoints directory' which is currently not documented.

[github-actions]

👈 Launch a Binder on branch sanaa-shaik/notebook/add-checkpoints-doc

[sanaa-shaik]

Hi! This PR adds documentation for checkpoints.
Could someone please add the appropriate label (likely docs)? Thank you!

[sanaa-shaik]

Hi! This PR is ready and all checks pass locally.
It seems the CI is failing due to missing labels.
Could someone please add the appropriate label? Thank you!

[sanaa-shaik]

Hi! Is anything else needed from my side for this PR?

[goelakash]

The amount of docs being added are substatantial - imo this could be simplified and compressed into a shorter addition