Fix broken link in mpotr blog post

Signed-off-by: David Goulet <dgoulet@ev0ke.net>

blog/index.html

@@ -96,7 +96,7 @@ common group key. Each of these have advantages and disadvantages, but details
 are being worked out to decide which one the next draft will follow.</p>
 <p>For the transcript consistency, the discussion was mostly about the performance
 overhead of the scheme described
-<a href="https://github.com/infinity0/msg-notes/blob/master/causal-02-consistency.rst">here</a>,
+<a href="https://github.com/infinity0/msg-notes/blob/master/causal/02-consistency.rst">here</a>,
 and whether simpler schemes achieve security guarantees that are strong enough.
 Again, I'm not going to go into more details since I feel that this would need
 its own blog post/paper and the goal here is to show what's being worked on