Updates an existing general appointment

patch https://api.alto.zoopladev.co.uk/appointments/general/{appointmentId}

Updates a general appointment with any of the following fields supported for update:

/startDate ie. The start date and time in ISO 8601 format to update against the requested general appointment
/endDate ie. The end date and time in ISO 8601 format to update against the requested general appointment
/negotiatorIds ie. An array of all negotiators' unique identifiers to be associated against the requested general appointment

Required scope: alto/write:appointments_general