Webhook Transaction Updated Event #174

Would be really cool if we could have webhook events that occurs on transaction updated events

For example
The notes are changed, an attachment is added or removed, category changed or tag added or removed

Even if this webhook batches or something to reduce the amount of times it fires off (Say the user in app is doing something, it sends the update events after a minute or two for all changes)

Or if a webhook optionally opts into update events so it won't spam webhook APIs with update events that aren't wanted