[增添]添加了datasource的setting数据库以及默认值

vendor/filament/forms/docs/04-layout/08-placeholder.md

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+---
+title: Placeholder
+---
+import AutoScreenshot from "@components/AutoScreenshot.astro"
+
+## Overview
+
+Placeholders can be used to render text-only "fields" within your forms. Each placeholder has `content()`, which cannot be changed by the user.
+
+```php
+use App\Models\Post;
+use Filament\Forms\Components\Placeholder;
+
+Placeholder::make('created')
+    ->content(fn (Post $record): string => $record->created_at->toFormattedDateString())
+```
+
+<AutoScreenshot name="forms/layout/placeholder/simple" alt="Placeholder" version="3.x" />
+
+> **Important:** All form fields require a unique name. That also applies to Placeholders!
+
+## Rendering HTML inside the placeholder
+
+You may even render custom HTML within placeholder content:
+
+```php
+use Filament\Forms\Components\Placeholder;
+use Illuminate\Support\HtmlString;
+
+Placeholder::make('documentation')
+    ->content(new HtmlString('<a href="https://filamentphp.com/docs">filamentphp.com</a>'))
+```
+
+## Dynamically generating placeholder content
+
+By passing a closure to the `content()` method, you may dynamically generate placeholder content. You have access to any closure parameter explained in the [advanced closure customization](../advanced#closure-customization) documentation:
+
+```php
+use Filament\Forms\Components\Placeholder;
+use Filament\Forms\Get;
+
+Placeholder::make('total')
+    ->content(function (Get $get): string {
+        return '€' . number_format($get('cost') * $get('quantity'), 2);
+    })
+```