chore(bip-0046): less ambiguous message prefix style

by @AdamISZ

Author: theborakompanioni

bip-0046.mediawiki

@@ -99,7 +99,7 @@ To derive the address from the above calculated public key and timelock, we crea
 
 In order to support signing of certificates, implementors should support signing ASCII messages.
 
-A certificate message can be created by another application external to this standard. It is then prepended with the string `\x18Bitcoin Signed Message:\n` and a byte denoting the length of the certificate message. The whole thing is then signed with the private key of the <tt>derived_key</tt>. This part is identical to the "Sign Message" function which many wallets already implement.
+A certificate message can be created by another application external to this standard. It is then prepended with the string `0x18 || "Bitcoin Signed Message:\n"` and a byte denoting the length of the certificate message. The whole thing is then signed with the private key of the <tt>derived_key</tt>. This part is identical to the "Sign Message" function which many wallets already implement.
 
 Almost all wallets implementing this standard can use their already-existing "Sign Message" function to sign the certificate message. As the certificate message itself is always an ASCII string, the wallet may not need to specially implement this section at all but just rely on users copypasting their certificate message into the already-existing "Sign Message" user interface. This works as long as the wallet knows how to use the private key of the timelocked address for signing messages.