Redraw contract lifecycle images, remove the rest of the page (#6550)

doc/docusaurus/docs/auction-smart-contract/end-to-end/closing-the-auction.md

@@ -13,3 +13,7 @@ This transaction needs to do the following:
 - Set a validity interval that starts no earlier than the auction's end time.
 
 The off-chain code for building and submitting this transaction will be very similar to the code for the bidding transactions, so the details are left as an exercise.
+
+Illustration of this transaction:
+
+![Settlement](../../../static/img/tx4.png)

doc/docusaurus/docs/auction-smart-contract/end-to-end/mint.md

@@ -89,3 +89,7 @@ node mint-token-for-auction.mjs
 
 and you should see a message "Minted a token at address ..." printed in the console.
 Within a minute, you should be able to find the transaction using the transaction hash on [Cardanoscan](https://preview.cardanoscan.io/) and review its details.
+
+Illustration of the minting transaction:
+
+![Minting the token](../../../static/img/tx1.png)

doc/docusaurus/docs/auction-smart-contract/end-to-end/placing-bids.md

@@ -45,6 +45,10 @@ node bid.mjs <minting-transaction-hash> bidder1 100000000
 Replace `<minting-transaction-hash>` with the hash of the transaction we previously submitted for minting the token.
 This hash is used by the off-chain code to locate the UTxO that contains the token.
 
+Illustration of the first bid:
+
+![First bid](../../../static/img/tx2.png)
+
 After the first bidding transaction is confirmed, we can submit the second bid from bidder2, with a similar command:
 
 ```
@@ -53,6 +57,10 @@ node bid.mjs <bidder1-transaction-hash> bidder2 200000000
 
 Replace `<bidder1-transaction-hash>` with the hash of the previous transaction.
 
+Illustration of the second bid:
+
+![Second bid](../../../static/img/tx3.png)
+
 ---
 
 [^1]: Instead of including the script in the transaction, we can use a reference script, but to keep things simple, we won't discuss that here.