Update TOC.yml

Author: rachel-msft

articles/postgresql/TOC.yml

@@ -149,6 +149,8 @@
       items:
       - name: Read replicas
         href: concepts-read-replicas.md
+      - name: Logical decoding
+        href: concepts-logical.md
   - name: Hyperscale (Citus)
     items:
     - name: Nodes