Fix WAN Replication / Advanced Features typo (#976)

Repeated `.`

(cherry picked from commit 8794935)

docs/modules/wan/pages/advanced-features.adoc

@@ -34,7 +34,7 @@ still communicate with WAN target clusters
 As well as failures such as the examples above, data can become out-of-sync
 after manual interventions such as cluster restarts or failover of one cluster
 to another (for example disaster recovery). **After any such situation, you are
-advised to synchronize all WAN replicated data.**.
+advised to synchronize all WAN replicated data**.
 
 To overcome this out-of-sync issue, you can use either of the following approaches
 to synchronize your WAN replicated clusters: