Revise title of Command Propagation section

Updated section title to include 'Recap' for clarity.

Author: TropicolX

stage_descriptions/replication-12-hd5.md

@@ -1,6 +1,6 @@
 In this stage, you'll extend your implementation of the master to support propagating commands to multiple replicas.
 
-### Command Propagation
+### Command Propagation (Recap)
 
 Once a replica completes the handshake and loads the RDB file, it is ready to start receiving live updates from the master.