Update eip-721 natspec

Author: C. Brown

EIPS/eip-721.md

@@ -73,9 +73,9 @@ interface ERC721 /* is ERC165 */ {
     function balanceOf(address _owner) external view returns (uint256);
 
     /// @notice Find the owner of an NFT
-    /// @param _tokenId The identifier for an NFT
     /// @dev NFTs assigned to zero address are considered invalid, and queries
     ///  about them do throw.
+    /// @param _tokenId The identifier for an NFT
     /// @return The address of the owner of the NFT
     function ownerOf(uint256 _tokenId) external view returns (address);