f - Clarify changelog downgrade note

Reword the backwards-compatibility note to call out that the downgrade
risk is limited to users who (1) manually persist
`Event::OnionMessageIntercepted` events and (2) opt in to the new
`intercept_for_unknown_scids` flag on
`OnionMessenger::new_with_offline_peer_interception`. LDK itself does
not persist these events, so anyone who doesn't persist them manually
is unaffected regardless of the flag.

Co-Authored-By: HAL 9000

Author: tnull

pending_changelog/4463-LSPS2-BOLT12.txt

@@ -1,5 +1,12 @@
 ## Backwards Compatibility
 
-When downgrading to LDK v0.2 and prior, `OnionMessageIntercepted` events that
-hold the new `NextMessageHop::ShortChannelId` will fail to be deserialized and
-hence will be discarded.
+If you manually persist `Event::OnionMessageIntercepted` events and construct
+your `OnionMessenger` via `OnionMessenger::new_with_offline_peer_interception`
+with `intercept_for_unknown_scids` set to `true`, you may not be able to
+downgrade to LDK v0.2 or prior: persisted events carrying the new
+`NextMessageHop::ShortChannelId` next hop will fail to deserialize on the
+older version.
+
+LDK does not persist `OnionMessageIntercepted` events itself. Users who do
+not persist these events manually, or who leave `intercept_for_unknown_scids`
+disabled, are unaffected.