91 interpolation

[emercado4]

Merge request template: please remove the appropriate parts of this template.

Pre-merge request checklist (to be completed by the one making the request):

• [x] I have performed a full review of this code myself.
  • For Python code in PySpark specific sections, all code should have been run in Jupyter notebooks.
  • For code in sections of the book containing both Python and R code, the page of the book should be constructed as described in the contributing guide and converted to a markdown file.
• [x] I have formatted the outputs of code blocks correctly (to match other outputs in the book and in line with the style guide [coming soon])
• [x] I have built the book as outlined in the contributing guide and confirmed that any additional/modified content is displaying as expected.

Details of this request:

• Adds interpolation.ipynb tip to analysis in spark section of the book
• Equivalent sparklyr code has also been added in.

Requirements for review (such as):

• [x] Check that the plot images display correctly
• [x] Check that the code tabs display correctly
• [x] Review text for readability, typos etc
• [x] Check that links all work correctly
• [x] Check that code works as expected

[emercado4]

Just one final change needs to be made to spark book links before merging, I agree with all other changes or comments

Thanks @Jday7879! I've edited the links now so hopefully this should be ready to merge :)