add payment link instruction

docs/pages/guides/sell-nft.mdx

@@ -52,10 +52,17 @@ If the NFT is on a different network than your current wallet is, you need to sw
 
 ### Create the listing
 
-Press the "Create" button and follow the steps in your wallet.
+Press the 'Create' button and follow the steps in your wallet.
 
 Once the listing is successfully created, you will be redirected to its detail page.
 
-Anyone can now buy your NFT using your marketplace.
+Anyone can now buy your NFT using your marketplace. If you don't have a marketplace, you can create a payment link (next step).
+
+### Optional - Payment link
+
+You can create a payment link to share on social networks or put on any website to sell your NFT in a few clicks.
+
+On the listing detail page, click the 'Create a payment link' button. Fill the **Redirection URL** and copy the payment link.
+After the user successfully purchase the NFT, it will be redirected to the URL indicated in **Redirection URL**.
 
 </Steps>