This addon updates routes when somene edits the slug for a page that has a collection mounted. The plugin will only update the routes configuration when there was already a route available.
Download the plugin and add it to your addons folder.
I'm my no means a skilled programmer at the time of writing. Feel free to treat this code as your own.
Brought to you by Studio 1902
Thanks to Mykolas & Bas de Kort for their help in learning backend programming.