Update onion-routing-htlc-forwarding.asciidoc

link to file name

onion-routing-htlc-forwarding.asciidoc

@@ -43,7 +43,7 @@ In all cases, some privacy of the payer and the recipient are lost.
 
 [[malicious-routing-diagram]]
 .If the Malicious node knows there are 2 layers left, then it knows that the payment recipient is either Node 19 (and there were only 19 hops) or one of Node 19's channel partners
-image:images/malicious-routing-diagram.png["If the Malicious node knows there are 2 layers left, then it knows that the payment recipient is either Node 19 (and there were only 19 hops) or one Node 19's channel partners"]
+image:images/malicious-routing-diagram.PNG["If the Malicious node knows there are 2 layers left, then it knows that the payment recipient is either Node 19 (and there were only 19 hops) or one Node 19's channel partners"]
 
 We can extend this example.
 Imagine a malicious entity sets up multiple Lightning nodes connected to other well-connected nodes, and it also connects itself across popular payment routes.