Update solmate-nft.md (#1256)

update `Ownable` constructor args.

src/tutorials/solmate-nft.md

@@ -136,7 +136,7 @@ contract NFT is ERC721, Ownable {
         string memory _name,
         string memory _symbol,
         string memory _baseURI
-    ) ERC721(_name, _symbol) {
+    ) ERC721(_name, _symbol) Ownable(msg.sender) {
         baseURI = _baseURI;
     }