fix(bridge): important details on DRT (#19)

## Description

While testing the Bridge Client, I've realized that we're missing some
important details on the Deposit Request Transaction (DRT) about:

1. that the multisig N-of-N is a Schnorr aggregated sig
1. that the `OP_RETURN` needs to be the first output

---

## Type of Change

- [ ] New Document
- [x] Update to Existing Document
- [ ] Bug Fix
- [ ] Question/clarification
- [ ] Other (please describe):

---

## Checklist

- [ ] I have reviewed the existing documentation to avoid duplication.
- [ ] The new or updated document includes clear and concise
information.
- [ ] All relevant sections (e.g., introduction, usage examples,
references)
      are included.
- [ ] The document follows the project's style guide and formatting
rules.
- [ ] I have included any necessary references or external resources.
- [ ] Spellcheck and grammar check have been performed.
- [ ] (For updates) I have verified that the changes reflect the current
state
      of the project.

---

## Reviewer Checklist

- [x] The purpose and scope of the document are clear.
- [x] The document is easy to understand and follow.
- [x] There are no typos or grammatical errors.
- [x] All necessary sections are included and well-structured.
- [x] The document is consistent with the project's style guide.
- [x] Any referenced links or resources are valid and appropriate.

---

**Thank you for contributing to our documentation!**

docs/technical/bitcoin-bridge.md

@@ -70,14 +70,20 @@ who sends 10[^fees] BTC to a P2TR address, where:
 1. The script path spend has two paths:
    1. "Deposit path", an $N$-of-$N$ multisig path,
       where $N$ is the number of operators in the bridge.
+      Note that this uses Schnorr key aggregation,
+      hence the signature is aggregated into a single signature that
+      validates all $N$ operators' signatures.
    1. "Take back" path,
       which allows the user to take back their funds if the bridge fails to
       move funds from the Deposit Request Transaction (DRT)
       into the bridge address within approximately 8.5 hours,
       i.e. it is time-locked and the user can spend it by providing a signature.
 
 This transaction has some metadata attached to it, in the form of an `OP_RETURN`
-output, that can be up to 80 bytes long (according to bitcoin standardness policy),
+output, that must be the **second** output of the transaction in order for the
+sequencer to be able to detect the transaction.
+The `OP_RETURN` output can be up to 80 bytes long
+(according to bitcoin standardness policy),
 and is composed of the following data:
 
 1. Magic bytes.

justfile

@@ -31,6 +31,7 @@ spell-check:
 spell-add *WORDS:
     @echo "Adding {{ WORDS }} to the dictionary"
     for word in {{ WORDS }}; do echo $word >> project-words.txt; done
+    @just spell-sort
 
 # Sort the dictionary
 spell-sort:

project-words.txt

@@ -1,6 +1,7 @@
 NUMS
 PUSHBYTES
 Rollkit
+Schnorr
 Taproot
 Tapscript
 Taptree