Update book author

[Jday7879]

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 (such as):

• Updated book authors

Reviewer Comments:

• Book authors has been updated and builds correctly

closes #81

[Jday7879]

Code has been reviewed and book is built correctly with new authors. Will merge