Add devdoc comments to IAssetData

contracts/asset-proxy/contracts/src/interfaces/IAssetData.sol

@@ -26,15 +26,26 @@ pragma experimental ABIEncoderV2;
 // This argument is ABI encoded as one of the methods of this interface.
 interface IAssetData {
 
+    /// @dev Function signature for encoding ERC20 assetData.
+    /// @param tokenAddress Address of ERC20Token contract.
     function ERC20Token(address tokenAddress)
         external;
     
+    /// @dev Function signature for encoding ERC721 assetData.
+    /// @param tokenAddress Address of ERC721 token contract.
+    /// @param tokenId Id of ERC721 token to be transferred.
     function ERC721Token(
         address tokenAddress,
         uint256 tokenId
     )
         external;
 
+    /// @dev Function signature for encoding ERC1155 assetData.
+    /// @param tokenAddress Address of ERC1155 token contract.
+    /// @param tokenIds Array of ids of tokens to be transferred. 
+    /// @param tokenValues Array of values that correspond to each token id to be transferred.
+    ///        Note that each value will be multiplied by the amount being filled in the order before transferring.
+    /// @param callbackData Extra data to be passed to receiver's `onERC1155Received` callback function.
     function ERC1155Assets(
         address tokenAddress,
         uint256[] calldata tokenIds,
@@ -43,12 +54,20 @@ interface IAssetData {
     )
         external;
 
+    /// @dev Function signature for encoding MultiAsset assetData.
+    /// @param amounts Array of amounts that correspond to each asset to be transferred.
+    ///        Note that each value will be multiplied by the amount being filled in the order before transferring.
+    /// @param nestedAssetData Array of assetData fields that will be be dispatched to their correspnding AssetProxy contract.
     function MultiAsset(
         uint256[] calldata amounts,
         bytes[] calldata nestedAssetData
     )
         external;
 
+    /// @dev Function signature for encoding StaticCall assetData.
+    /// @param callTarget Contract that will execute the staticcall.
+    /// @param staticCallData Data that will be executed via staticcall on the callTarget contract.
+    /// @param callResultHash Keccak256 hash of the expected staticcall return data. 
     function StaticCall(
         address callTarget,
         bytes calldata staticCallData,