docs: add state transaction.lockupFailed (#513)

* docs: No subject

* docs: add state transaction.lockupFailed

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Co-authored-by: Kilian <kilian.rausch@gmail.com>

docs/lifecycle.md

@@ -32,7 +32,7 @@ When a Normal Submarine Swap is created, it passes through the following states:
 6. `transaction.claim.pending`: This status indicates that Boltz is ready for the creation of a cooperative signature for a keypath spend. Taproot Swaps are not claimed immediately by Boltz after the invoice has been paid, but instead Boltz waits for the API client to post a signature for a key path spend. If the API client does not cooperate in a key path spend, Boltz will eventually claim via the script path.
 7. `transaction.claimed`: indicates that after the invoice was successfully paid, the chain Bitcoin were successfully claimed _by Boltz_. This is the final status of a successful Normal Submarine Swap.
 
-If the user doesn't send chain bitcoin and the swap expires (approximately 24h), Boltz will set the state of the swap to `swap.expired` , which means that it was cancelled and chain bitcoin shouldn't be sent anymore. In case of `invoice.failedToPay` or `swap.expired` but bitcoin were sent, the user needs to submit a refund transaction to reclaim their locked chain bitcoin. For more information about how Boltz API clients can construct & submit refund transactions for users, check the [Claiming Swaps & Refunds](claiming-swaps.md) section. The states `invoice.failedToPay` and `swap.expired` are final since Boltz is _not_ monitoring refund transactions on the chain.
+If the user doesn't send chain bitcoin and the swap expires (approximately 24h), Boltz will set the state of the swap to `swap.expired` , which means that it was cancelled and chain bitcoin shouldn't be sent anymore. In case of the states `invoice.failedToPay` or `swap.expired` but bitcoin were sent or `transaction.lockupFailed` , which usually is set if the user sent too little, the user needs to submit a refund transaction to reclaim their locked chain bitcoin. For more information about how Boltz API clients can construct & submit refund transactions for users, check the [Claiming Swaps & Refunds](claiming-swaps.md) section. The states `invoice.failedToPay` and `swap.expired` are final since Boltz is _not_ monitoring refund transactions on the chain.
 
 ### Reverse Submarine Swaps