Add ERC-721 Enumerable extension section

Author: Pabl0cks

extension/README.md.args.mjs

@@ -6,6 +6,8 @@ The ERC-721 Token Standard introduces a standard for Non-Fungible Tokens ([EIP-7
 
 The ERC-721 token contract is implemented using the [ERC-721 token implementation](https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC721/ERC721.sol) from OpenZeppelin.
 
+The ERC-721 token implementation uses the [ERC-721 Enumerable extension](https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC721/extensions/ERC721Enumerable.sol) from OpenZeppelin to list all tokens from the collection and all the tokens owned by an address. You can remove this if you plan to use an indexer, like a Subgraph or Ponder ([extensions available](https://scaffoldeth.io/extensions)).
+
 ### Setup
 
 Deploy your contract running \`\`\`yarn deploy\`\`\`