docs: committed bookings accept participants without email on the test system

docs/bpn-xml-api-reference.md

@@ -176,7 +176,8 @@ is stricter than what BusPro applies to ordinary participants.
 `650 … 1.Teilnehmer-Mail-Adresse, 2.Teilnehmer-Mail-Adresse`, while an email identical to the Anmelder's
 was accepted. On 2026-10-15 the requirement was switched off on the test system, and the same requests
 (no `email`, no `kommunikation`, an empty `<email/>`, adults and children, with and without a travelling
-Anmelder) all pass with an unchanged price. BusPro now accepts a participant without an email at any age,
+Anmelder) all pass with an unchanged price. A committed `Buchung` (status `A`) with an email-less child
+goes through as well, both with a travelling Anmelder and with one who does not travel. BusPro now accepts a participant without an email at any age,
 so the rule MyE&P applies (required from 16, and for the applicant at any age) is enforced only by
 `ParticipantDto` and `BookingDto` validation. Production needs the same configuration before under-16s
 without an email can be booked there.