quickstart clustering doc update

[gtduncan]

Describe your changes

Edited quickstart clustering doc so that instead of manually creating a PCA visualization it uses our API's plot.pca function

Issue ticket number and link

Closes #276

Checklist before requesting a review

• [x] I have performed a self-review of my code
• [x] I have added thorough tests (when necessary).
• [x] I have added the right documentation in the docstring and changelog (when needed)

---

:books: Documentation preview :books:: https://sklearn-evaluation--288.org.readthedocs.build/en/288/

[coveralls]

Pull Request Test Coverage Report for Build 4189243772

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 94.15%

---

Totals
Change from base Build 4187981624:	0.0%
Covered Lines:	3042
Relevant Lines:	3231

---

💛 - Coveralls