fix(musig): html code rendering

Author: GabrieleBocchi

decoding/musig.mdx

@@ -438,10 +438,9 @@ Where:
 ### Final Signature
 
 The final aggregate signature is:
+<code>(R<span className="text-xs align-sub">agg</span>, s<span className="text-xs align-sub">agg</span>)</code>
 
-`(R<span className="text-xs align-sub">agg</span>, s<span className="text-xs align-sub">agg</span>)`
-
-This pair can be verified using `P<span className="text-xs align-sub">agg</span>` and the message `m`.
+This pair can be verified using <code>P<span className="text-xs align-sub">agg</span></code> and the message `m`.
 
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