docs: Update the example to set up black formatter in Python (#13839)

As titled. The new example is consistent with the instructions in
"Configuring Zed". I verified that the example works as expected.

Release Notes:

- Update the instructions to set up external formatter for Python.
1bd585186aZhangfan committed on 7/5/2024, 1:32:48 PM· committed by GitHubparente69f9d6
1 file changedLine totals unavailable