Fix filename case

Author: jonels-msft

articles/postgresql/TOC.yml

@@ -698,7 +698,7 @@
         - name: Node.js
           href: hyperscale/howto-app-stacks-nodejs.md
         - name: C#
-          href: hyperscale/howto-app-stacks-Csharp.md
+          href: hyperscale/howto-app-stacks-csharp.md
         - name: Java
           href: hyperscale/howto-app-stacks-java.md
         - name: Ruby

articles/postgresql/hyperscale/howto-app-stacks-Csharp.md renamed to articles/postgresql/hyperscale/howto-app-stacks-csharp.md

@@ -20,7 +20,7 @@ to create, read, update, and delete data.
 
 * [Python](howto-app-stacks-python.md)
 * [Node JS](howto-app-stacks-nodejs.md)
-* [C#](howto-app-stacks-Csharp.md)
+* [C#](howto-app-stacks-csharp.md)
 * [Java](howto-app-stacks-java.md)
 * [Ruby](howto-app-stacks-ruby.md)