Add require login feature to see gists

public/admin.ts

@@ -1,5 +1,6 @@
 document.addEventListener('DOMContentLoaded', () => {
     registerDomSetting(document.getElementById('disable-signup') as HTMLInputElement);
+    registerDomSetting(document.getElementById('require-login') as HTMLInputElement);
 });
 
 const setSetting = (key: string, value: string) => {