Add gemini manifest

Author: marzvrover

gemini-extension.json

@@ -0,0 +1,12 @@
+{
+	"name": "github",
+	"version": "1.0.0",
+	"mcpServers": {
+		"github": {
+			"httpUrl": "https://api.githubcopilot.com/mcp",
+			"headers": {
+				"Authorization": "Bearer $GITHUB_MCP_PAT"
+			}
+		}
+	}
+}