Update TOC.yml

Author: xboxeer

articles/mysql/TOC.yml

@@ -31,6 +31,8 @@
             href: flexible-server/release-notes/january-2024.md
           - name: February 2024
             href: flexible-server/release-notes/february-2024.md
+          - name: April 2024
+            href: flexible-server/release-notes/april-2024.md            
       - name: Compute and storage
         href: flexible-server/concepts-service-tiers-storage.md
   - name: Quickstarts