Add docs

contracts/handlers/DefaultMessageReceiver.sol

@@ -8,6 +8,10 @@ import "@openzeppelin/contracts/token/ERC1155/utils/ERC1155Holder.sol";
 import "../utils/AccessControl.sol";
 import "../interfaces/ISygmaMessageReceiver.sol";
 
+/**
+    @title Optinal Message Call made as part of other handlers proposal execution.
+    @author ChainSafe Systems.
+ */
 contract DefaultMessageReceiver is ISygmaMessageReceiver, AccessControl, ERC721Holder, ERC1155Holder {
     bytes32 public constant SYGMA_HANDLER_ROLE = keccak256("SYGMA_HANDLER_ROLE");
 
@@ -45,10 +49,10 @@ contract DefaultMessageReceiver is ISygmaMessageReceiver, AccessControl, ERC721H
         uint256 amount
     );
 
-    /// Constructor ///
-
-    /// @param sygmaHandlers The contract addresses with access to message processing.
-    /// @param recoverGas The amount of gas needed to forward the original amount to receiver.
+    /**
+        @param sygmaHandlers The contract addresses with access to message processing.
+        @param recoverGas The amount of gas needed to forward the original amount to receiver.
+     */
     constructor(address[] memory sygmaHandlers, uint256 recoverGas) {
         _recoverGas = recoverGas;
         _setupRole(DEFAULT_ADMIN_ROLE, msg.sender);
@@ -68,6 +72,12 @@ contract DefaultMessageReceiver is ISygmaMessageReceiver, AccessControl, ERC721H
         specified in this particular Action.tokenReceive property. In such a case it is
         a users responsibility to either send it all with a transferBalanceAction() Action or to
         include an extra action[s] with tokenReceive set to each of the tokens received.
+        @param tokenSent Optional address of the token sent along or prior to calling this function.
+        @param amount Amount of the token sent along or prior to calling this function.
+        @param message User generated execution command which consists of
+        {transactionId} an arbitrary identifier.
+        {actions} array of Action items that allow generic logic execution.
+        {receiver} a fallback address that will receive any leftovers after either success of fail.
      */
     function handleSygmaMessage(
         address tokenSent,
@@ -183,8 +193,12 @@ contract DefaultMessageReceiver is ISygmaMessageReceiver, AccessControl, ERC721H
         }
     }
 
-    /// @notice Helper function that could be used as an Action to itself to transfer whole
-    /// @notice balance of a particular token.
+    /**
+        @notice Helper function that could be used as an Action to itself to transfer whole
+        balance of a particular token.
+        @param token Address of the ERC20 token or 0x0 for native token.
+        @param receiver Address that should receive the whole balance.
+     */
     function transferBalanceAction(address token, address receiver) external {
         if (msg.sender != address(this)) revert InsufficientPermission();
         if (token != zeroAddress) {

contracts/handlers/ERC20Handler.sol

@@ -21,6 +21,7 @@ contract ERC20Handler is IHandler, ERCHandlerHelpers, DepositDataHelper, ERC20Sa
 
     /**
         @param bridgeAddress Contract address of previously deployed Bridge.
+        @param defaultMessageReceiver Contract address of previously deployed DefaultMessageReceiver.
      */
     constructor(
         address bridgeAddress,