Adding TOC

Author: SnehaGunda

articles/cosmos-db/TOC.yml

@@ -595,6 +595,8 @@
         items:
         - name: Elastic scale
           href: manage-scale-cassandra.md
+        - name: 
+          href: cassandra-secondary-index.md
       - name: How-to guides
         items:
         - name: Change feed

articles/cosmos-db/cassandra-secondary-index.md

@@ -23,7 +23,7 @@ It's not advised to create index on a frequently updated column. It is prudent t
 > * Static columns
 > * Clustering keys
 
-## Create 
+## Create an index
 
 ### Create a table
 Use the following commands to create a key space and a table: