Fix links in setup.md for curriculum usage

[sunnynagavo]

This pull request makes minor improvements to the setup.md file by correcting internal links to ensure they work properly in the documentation.

• Link corrections:

  • Updated the link to the instructions for running code notebooks from ./etc/how-to-run.md to ./how-to-run.md for accuracy.
  • Changed the link to the teacher suggestions file from an absolute path /for-teachers.md to a relative path ./for-teachers.md for consistency.

  Fixes #568

[sunnynagavo]

@leestott There is still one issue

if you look at this text: "A note about quizzes: All quizzes are contained in this app, for 50 total quizzes..."

is the Azure static app down ? I cant access the quizzes page and none of the links in the entire repo with red-field url works.

[leestott]

@sunnynagavo so all the quizzes are here https://ff-quizzes.netlify.app/en/