Fix NatSpec comment syntax

contracts/metatx/ERC2771Context.sol

@@ -4,7 +4,7 @@ pragma solidity ^0.8.0;
 
 import "../utils/Context.sol";
 
-/*
+/**
  * @dev Context variant with ERC2771 support.
  */
 abstract contract ERC2771Context is Context {

contracts/metatx/MinimalForwarder.sol

@@ -5,7 +5,7 @@ pragma solidity ^0.8.0;
 import "../utils/cryptography/ECDSA.sol";
 import "../utils/cryptography/draft-EIP712.sol";
 
-/*
+/**
  * @dev Simple minimal forwarder to be used together with an ERC2771 compatible contract. See {ERC2771Context}.
  */
 contract MinimalForwarder is EIP712 {

contracts/utils/Context.sol

@@ -2,7 +2,7 @@
 
 pragma solidity ^0.8.0;
 
-/*
+/**
  * @dev Provides information about the current execution context, including the
  * sender of the transaction and its data. While these are generally available
  * via msg.sender and msg.data, they should not be accessed in such a direct