Docs add packages url to updates

What does this MR do?

The [maintenance](https://docs.gitlab.com/ee/policy/maintenance.html page shows samples of updating to a specific version but we don't highlight where these versions can be found.

This merge request is to add that detail.

Related issues

Customer support ticket (https://gitlab.zendesk.com/agent/tickets/150883) internal use only.

Author's checklist

• Follow the Documentation Guidelines and Style Guide.
• Apply the documentation label.

Review checklist

All reviewers can help ensure accuracy, clarity, completeness, and adherence to the Documentation Guidelines and Style Guide.

2. Technical Writer

• Optional: Technical writer review. If not requested for this MR, must be scheduled post-merge. To request for this MR, assign the writer listed for the applicable DevOps stage.

3. Maintainer

1. Review by assigned maintainer, who can always request/require the above reviews. Maintainer's review can occur before or after a technical writer review.
2. Ensure a release milestone is set.
3. If there has not been a technical writer review, create an issue for one using the Doc Review template.