Merge pull request #9577 from microsoft/ntrogh/banner-config

Add website banner config

Author: ntrogh

build/banner.json

@@ -0,0 +1,7 @@
+{
+  "enabled": true,
+  "version": "2026-03-17-ghcp-events",
+  "message": "Explore Agentic Development -",
+  "linkText": "Join a GitHub Copilot Dev Day near you!",
+  "linkUrl": "https://aka.ms/githubcopilotdevdays"
+}