Fix materialized view link

Author: seesharprun

articles/cosmos-db/cassandra/TOC.yml

@@ -268,7 +268,7 @@
             - name: Overview            
               href: materialized-views.md
             - name: FAQ
-              href: materialized-views-faq.md
+              href: materialized-views-faq.yml
         - name: Lightweight Transactions in API for Apache Cassandra
           href: lightweight-transactions.md
         - name: Change feed for API for Apache Cassandra