Add filter to edit $description synced to gCal

[Valentina R]

In file \woocommerce-appointments\includes\class-wc-appointments-gcal.php on line 875 (before syncing the resource) add a filter to modify the $description data.

Requested here.

[Željan Topić]

Filter 'woocommerce_appointments_gcal_sync_order_meta' already present for this

[Valentina R]

The issue is that that's in a foreach loop and doesn't have the appointment object or ID which this user needs.