Add SEP-24 withdrawal flow docs (#178)

* Add SEP-24 docs

* Fix review comments

docs/building-apps/wallet/sep24.mdx

@@ -72,9 +72,7 @@ const asset = info.currencies.find(({ code }) => code === "USDC").assetId;
 
 :::info
 
-[//]: # "TODO: link to establish trustline guide"
-
-Before starting with the deposit flow, make sure that the user account has established a trustline for the asset you are working with.
+Before starting with the deposit flow, make sure that the user account has [established a trustline](/docs/building-apps/wallet/stellar#modify-assets-trustlines) for the asset you are working with.
 
 :::
 
@@ -294,7 +292,7 @@ This code example will consume all events coming from the channel until it's clo
 
 :::info
 
-Events are stored in the channel until they are received, and calling the `receive()` method will block the channel until a message is received. You can read more about how channels work in the [channel documentation].(https://kotlinlang.org/docs/coroutines-and-channels.html#channels).
+Events are stored in the channel until they are received, and calling the `receive()` method will block the channel until a message is received. You can read more about how channels work in the [channel documentation](https://kotlinlang.org/docs/coroutines-and-channels.html#channels).
 
 :::
 
@@ -334,6 +332,96 @@ const transactions = await anchor.getTransactionsForAsset({
 
 </CodeExample>
 
+## Submitting Withdrawal Transfer
+
+Previously, we took a look at starting the withdrawal flow. Now, let's take a look at a full example.
+
+First, start the withdrawal:
+
+<CodeExample>
+
+```kt
+val withdrawal = sep24.withdraw(asset, authToken = token)
+```
+
+</CodeExample>
+
+Next, open an interactive url :
+
+<CodeExample>
+
+```kt
+val url = withdrawal.url
+// open the url
+```
+
+</CodeExample>
+
+After that we need to wait until the anchor is ready to receive funds. To do so, we will be waiting until transaction reaches `pending_user_transfer_start` status
+
+<CodeExample>
+
+```kt
+val withdrawalWatcher = sep24.watcher().watchOneTransaction(token, withdrawal.id)
+var statusChange: StatusUpdateEvent
+
+// Wait for user input
+do {
+  statusChange = withdrawalWatcher.channel.receive()
+} while (
+  ((statusChange as? StatusChange) ?: throw Exception("Channel unexpectedly closed"))
+    .status != TransactionStatus.PENDING_USER_TRANSFER_START
+)
+```
+
+</CodeExample>
+
+Next, sign and submit the Stellar transfer:
+
+<CodeExample>
+
+```kt
+val anchorTransaction = (statusChange.transaction as WithdrawalTransaction)
+val transfer = stellar.transaction(keypair).transferWithdrawalTransaction(anchorTransaction, asset).build()
+
+transfer.sign(keypair)
+
+stellar.submitTransaction(transfer)
+```
+
+</CodeExample>
+
+Where `keypair` is the SEP-10 authenticated account. If you want to transfer funds from a different address, refer to [Changing Stellar Transfer Account](#changing-stellar-transfer-account) section.
+
+Finally, let's track transaction status updates. In this example we simply check if the transaction has been completed:
+
+<CodeExample>
+
+```kt
+var terminalStatus: TransactionStatus? = null
+
+do {
+  statusChange = withdrawalWatcher.channel.receive()
+
+  when (statusChange) {
+    is StatusChange -> {
+      if (statusChange.status.isTerminal()) {
+        terminalStatus = statusChange.status
+      }
+    }
+    is ChannelClosed -> println("Transaction tracking finished")
+    is ExceptionHandlerExit ->
+      println("Retries exhausted trying obtain transaction data, giving up.")
+  }
+} while (statusChange !is ChannelClosed)
+
+if (terminalStatus != TransactionStatus.COMPLETED) {
+  println("Transaction was not completed")
+}
+```
+
+</CodeExample>
+
 [sep-9]: https://github.com/stellar/stellar-protocol/blob/master/ecosystem/sep-000p.md
 [sep-10]: https://github.com/stellar/stellar-protocol/blob/master/ecosystem/sep-0010.md
 [sep-24]: https://github.com/stellar/stellar-protocol/blob/master/ecosystem/sep-0024.md