make key poitn bold

Author: jrakibi

decoding/utxo.mdx

@@ -65,7 +65,8 @@ To spend 7 BTC, Bob has multiple options:
 
 1. Use the 5 BTC and 3 BTC UTXOs and receive 1 BTC back as 'change' (a new UTXO).
 2. Alternatively, use the 5 BTC and 2 BTC UTXOs without needing any change.
-   Key Points:
+   
+**Key Points:**
 
 -   UTXOs can only be spent once (like using a paper bill)
 -   Each transaction creates new UTXOs