Update 0012_ibc_generic_messaging.md with permissionless channel creation information (#4167)

The `wormhole-ibc-receiver` contract contains an allowlist of Wormhole chain ID to channel mappings (other side of Cosmos chain). The allowlist is not used when receiving a packet because we don't want to handle the case of a token transfer failure on the other side. Instead, we just emit the message and ignore it in the IBC watcher. I am just updating the documentation to reflect this.

whitepapers/0012_ibc_generic_messaging.md

@@ -48,7 +48,7 @@ The `wormhole-ibc` contract is meant to replace the `wormhole` core bridge contr
 
 Sending an IBC packet requires choosing an IBC channel to send over. Since IBC `(channel_id, port_id)` pairs are unique, we maintain a state variable on the `wormhole-ibc` contract that whitelists the IBC channel to send messages to the `wormchain-ibc-receiver` contract. This variable can be updated through a new governance VAA type `IbcReceiverUpdateChannelChain`.
 
-The `wormchain-ibc-receiver` contract will be deployed on Wormchain and is meant to receive the IBC messages the `wormhole-ibc` contract sends from various IBC enabled chains. Its responsibility is to receive the IBC message, perform validation, emit the message for the guardian node to observe, and then send an IBC acknowledgement to the source chain. This contract also maintains a whitelist mapping IBC channel IDs to Wormhole Chain IDs. The whitelist can be updated through the `IbcReceiverUpdateChannelChain` governance VAA type as well.
+The `wormchain-ibc-receiver` contract will be deployed on Wormchain and is meant to receive the IBC messages the `wormhole-ibc` contract sends from various IBC enabled chains. Its responsibility is to receive the IBC message, perform validation, emit the message for the guardian node to observe, and then send an IBC acknowledgement to the source chain. In order to not handle failed transfers on the `wormhole-ibc` contract, the mechanism is permissionless to establish a channel and emit events. This contract maintains a whitelist mapping IBC channel IDs to Wormhole Chain IDs that get processed via the Guardian IBC Watcher with all others being ignored by the watcher. The whitelist can be updated through the `IbcReceiverUpdateChannelChain` governance VAA type as well.
 
 ### IBC Relayers