Fix incorrect Credits model for Kirigami.AboutPage

Summary:
Credits section currently displays the list of translators.

This fixes a copy-paste mistake.

Test Plan: Opened Discover's About page with and without the change; after the fix, the Credits section disappeared.

Reviewers: Kirigami, apol

Reviewed By: apol

Subscribers: plasma-devel

Tags: Kirigami

Differential Revision: https://phabricator.kde.org/D24768