Misc documentation and comment updates

cumulus/parachains/runtimes/assets/asset-hub-rococo/src/xcm_config.rs

@@ -846,8 +846,8 @@ pub mod bridging {
 			/// (initially was calculated by test `OutboundQueue::calculate_fees` - ETH/ROC 1/400 and fee_per_gas 20 GWEI = 2200698000000 + *25%)
 			/// Needs to be more than fee calculated from DefaultFeeConfig FeeConfigRecord in snowbridge:parachain/pallets/outbound-queue/src/lib.rs
 			/// Polkadot uses 10 decimals, Kusama and Rococo 12 decimals.
-			pub const DefaultBridgeHubEthereumBaseFee: u128 = 2_750_872_500_000;
-			pub storage BridgeHubEthereumBaseFee: u128 = DefaultBridgeHubEthereumBaseFee::get();
+			pub const DefaultBridgeHubEthereumBaseFee: Balance = 2_750_872_500_000;
+			pub storage BridgeHubEthereumBaseFee: Balance = DefaultBridgeHubEthereumBaseFee::get();
 			pub SiblingBridgeHubWithEthereumInboundQueueInstance: MultiLocation = MultiLocation::new(
 				1,
 				X2(

cumulus/parachains/runtimes/bridge-hubs/bridge-hub-rococo/src/bridge_to_ethereum_config.rs

@@ -21,6 +21,7 @@ use crate::{
 use snowbridge_rococo_common::EthereumNetwork;
 use snowbridge_router_primitives::outbound::EthereumBlobExporter;
 
+/// Exports message to the Ethereum Gateway contract.
 pub type SnowbridgeExporter = EthereumBlobExporter<
 	UniversalLocation,
 	EthereumNetwork,

cumulus/parachains/runtimes/bridge-hubs/bridge-hub-rococo/src/xcm_config.rs

@@ -388,6 +388,8 @@ impl cumulus_pallet_xcm::Config for Runtime {
 	type XcmExecutor = XcmExecutor<XcmConfig>;
 }
 
+/// Creates an AgentId from a MultiLocation. An AgentId is a unique mapping to a Agent contract on
+/// Ethereum which acts as the sovereign account for the MultiLocation.
 pub type AgentIdOf = HashedDescription<H256, (DescribeHere, DescribeFamily<DescribeAllTerminal>)>;
 
 /// A `HandleFee` implementation that simply deposits the fees for `ExportMessage` XCM instructions

cumulus/parachains/runtimes/bridge-hubs/common/src/message_queue.rs

@@ -40,6 +40,9 @@ pub enum AggregateMessageOrigin {
 	///
 	/// This is used by the HRMP queue.
 	Sibling(ParaId),
+	/// The message came from a snowbridge channel.
+	/// 
+	/// This is used by Snowbridge inbound queue.
 	Snowbridge(ChannelId),
 }
 
@@ -109,6 +112,9 @@ where
 	}
 }
 
+/// Narrow the scope of the `Inner` query from `AggregateMessageOrigin` to `ParaId`.
+///
+/// All non-`Sibling` variants will be ignored.
 pub struct NarrowOriginToSibling<Inner>(PhantomData<Inner>);
 impl<Inner: QueuePausedQuery<ParaId>> QueuePausedQuery<AggregateMessageOrigin>
 	for NarrowOriginToSibling<Inner>