Add VarDumper collector docs

docs/en/collector/var-dumper.md

@@ -0,0 +1,60 @@
+# Collectors
+
+## [VarDumper collector](./../../../src/Collector/VarDumperCollector.php)
+
+`VarDumperCollector` collects all data dumped
+by [`\Yiisoft\Yii\Debug\VarDumper\VarDumper`](https://github.com/yiisoft/var-dumper/blob/master/src/VarDumper.php) or
+its shortcut functions `dump()`, `d` and `dd()`.
+
+It uses [`\Yiisoft\Yii\Debug\Collector\VarDumperHandlerInterfaceProxy`](./../../../src/Collector/VarDumperHandlerInterfaceProxy.php) proxy to wrap the original VarDumper's [`HandlerInterface`](https://github.com/yiisoft/var-dumper/blob/master/src/HandlerInterface.php) and proxy all calls to the collector.
+
+## Collected data
+
+### Common
+
+Example:
+
+```php
+final class SiteController
+{
+    public function __construct(private ViewRenderer $viewRenderer)
+    {
+        $this->viewRenderer = $viewRenderer->withController($this);
+    }
+
+    public function index(): ResponseInterface
+    {
+        d(['test'], 1, new stdClass());
+        return $this->viewRenderer->render('index');
+    }
+}
+```
+
+Output:
+
+```json
+[
+    {
+        "variable": [
+            "test"
+        ],
+        "line": ".../demo\/blog\/src\/Controller\/SiteController.php:20"
+    },
+    {
+        "variable": 1,
+        "line": ".../demo\/blog\/src\/Controller\/SiteController.php:20"
+    },
+    {
+        "variable": "object@stdClass#7735",
+        "line": ".../demo\/blog\/src\/Controller\/SiteController.php:20"
+    }
+]
+```
+
+### Summary
+
+```json
+{
+    "total": 3
+}
+```

docs/en/index.md

@@ -9,6 +9,7 @@
 - [Main concept](./collector.md)
 - [Summary collectors](./collector/summary.md)
 - [Service Collector](./collector/service.md)
+- [VarDumper Collector](./collector/var-dumper.md)
 
 ## Console commands
 - [`debug:reset`](./command-reset.md)