add refactoring learning objectives

[carriewright11]

adding learning objectives for the refactoring chapter

[github-actions[bot]]

No spelling errors! :tada: Comment updated at 2023-06-08 with changes from 2b4db6d8324bef36c5b6f9f428fec360d15307a1

[github-actions[bot]]

No broken urls! :tada: Comment updated at 2023-06-08 with changes from 2b4db6d8324bef36c5b6f9f428fec360d15307a1

[github-actions[bot]]

Re-rendered previews from the latest commit:

• See preview of Bookdown here
• See preview of Coursera/Leanpub version here
• Download the preview of .docx file

Updated at 2023-06-08 with changes from 2b4db6d8324bef36c5b6f9f428fec360d15307a1

[carriewright11]

I fixed these spelling errors in another PR. So we can merge main into here after we merge that one.