Update Discord image to be more reliable

Author: justinyoo

README.md

@@ -1,6 +1,6 @@
 # Model Context Protocol .NET Samples
 
-[![Azure AI Community Discord](https://dcbadge.vercel.app/api/server/ByRwuEEgH4)](https://discord.com/invite/ByRwuEEgH4)
+[![Azure AI Community Discord](https://dcbadge.limes.pink/api/server/ByRwuEEgH4)](https://discord.com/invite/ByRwuEEgH4)
 
 ## 🚀 Introduction