fix formating issue

Author: jrakibi

decoding/inputs-prev-txid.mdx

@@ -138,7 +138,8 @@ This difference in segwit transactions was intentionally designed to prevent tra
 There was a unique situation in Bitcoin's history where duplicate TXIDs occurred in blocks 91,722 and 91,880. This led to:
 
 1. BIP 30: Preventing blocks from containing duplicate TXIDs
-2. BIP 34: Requiring coinbase transactions to include block height in their data
+2. BIP 34: Requiring coinbase transactions to include block height in their data.
+
 </ExpandableAlert>
 
 ## Implementation Details