Document common autorouter prop strings on the Custom Autorouting page

[seveibar]

https://docs.tscircuit.com/web-apis/autorouting-api#using-custom-autorouters

[seveibar]

or at least link to this section: https://docs.tscircuit.com/elements/board#setting-the-autorouter

[github-actions]

This issue has been automatically marked as stale because it has had no recent activity. It will be closed if no further activity occurs.

[github-actions]

This issue was closed because it has been inactive for 14 days since being marked as stale.