Update code examples

Author: cleptric

src/platform-includes/configuration/before-send-transaction/php.laravel.mdx

@@ -1,8 +1,8 @@
 In the Laravel config, a closure can be used to modify the event or return a completely new one. If you return `null`, the event will be discarded.
 
 ```php {filename:config/sentry.php}
-'before_send_transaction' => function (\Sentry\Event $event): ?\Sentry\Event {
-    return $event;
+'before_send_transaction' => function (\Sentry\Event $transaction): ?\Sentry\Event {
+    return $transaction;
 },
 ```
 

src/platform-includes/configuration/before-send-transaction/php.mdx

@@ -3,8 +3,8 @@ In PHP, a closure can be used to modify the event or return a completely new one
 ```php
 \Sentry\init([
     'dsn' => '___PUBLIC_DSN___',
-    'before_send_transaction' => function (\Sentry\Event $event): ?\Sentry\Event {
-        return $event;
+    'before_send_transaction' => function (\Sentry\Event $transaction): ?\Sentry\Event {
+        return $transaction;
     },
 ]);
 ```