docs(stalwart): white-label groupware defaults in the bootstrap notes

Stalwart names every account's default calendar 'Stalwart Calendar' and
address book 'Stalwart Address Book' — visible in Apple Calendar/Contacts.
Set to neutral 'Calendar'/'Contacts' on the live server (x:Calendar +
x:AddressBook singletons via management JMAP, existing ronni@dezky.eu
collections renamed); recorded as bootstrap step 4 for rebuilds.

infrastructure/production/host/stalwart/install.sh

@@ -152,6 +152,10 @@ warn "      2. via JMAP (basic auth, those creds): x:Domain/set create the"
 warn "         primary domain, then x:Account/set create name=admin in it with"
 warn "         roles {\"@type\":\"Admin\"} and a Password credential"
 warn "      3. remove the two STALWART_RECOVERY_* lines, restart again"
+warn "      4. white-label the groupware defaults via management JMAP:"
+warn "         x:Calendar/set + x:AddressBook/set update singleton"
+warn "         defaultDisplayName -> 'Calendar' / 'Contacts' (Stalwart ships"
+warn "         'Stalwart Calendar'/'Stalwart Address Book')"
 warn "  • PTR/rDNS for the server IP MUST be 'mail.dezky.eu' (Hetzner Robot)."
 warn "  • Publish DNS at simply.com: MX → mail.dezky.eu, SPF, DMARC; per-domain"
 warn "    DKIM records come from Stalwart's dnsZoneFile via platform-api."