PYTHON-5797 - Add IWM and Overload Error links to changelog

[NoahStapp]

PYTHON-5797

Changes in this PR

Add links for the IWM and Overload Error docs pages to the changelog.

Test Plan

Checklist

Checklist for Author

• Did you update the changelog (if necessary)?
• Is there test coverage?
• Is any followup work tracked in a JIRA ticket? If so, add link(s).

Checklist for Reviewer

• Does the title of the PR reference a JIRA Ticket?
• Do you fully understand the implementation? (Would you be comfortable explaining how this code works to someone else?)
• Is all relevant documentation (README or docstring) updated?

[Copilot]

Pull request overview

Updates the PyMongo 4.17.0 changelog entry to reference the new MongoDB Atlas documentation pages for Intelligent Workload Management (IWM) and overload errors.

Changes:

• Replaces internal placeholders with public documentation links for IWM.
• Adds a public documentation link for overload errors in the same changelog bullet.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.