add domain validation + custom dns servers

add new guides / docs

database/migrations/2024_01_15_084609_add_custom_dns_server.php

@@ -0,0 +1,30 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::table('instance_settings', function (Blueprint $table) {
+            $table->boolean('is_dns_validation_enabled')->default(true);
+            $table->string('custom_dns_servers')->nullable()->default('1.1.1.1');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('instance_settings', function (Blueprint $table) {
+            $table->dropColumn('is_dns_validation_enabled');
+            $table->dropColumn('custom_dns_servers');
+        });
+    }
+};