docs: Switch to validateData method in Uploaded FIles example

[stuart897]

Fixes #8430

[kenjis]

In fact, in this case $_POST is an empty array. So $postData doesn't matter.
But is this better? Since it works even when other fields are present.

Suggested change

	$postData = ['userfile' => $this->request->getPost('userfile')];
	$postData = $this->request->getPost(array_keys($validationRule));

[kenjis]

Please fix coding style.
Run composer cs-fix to fix.
See https://github.com/codeigniter4/CodeIgniter4/blob/develop/contributing/pull_request.md#php-style

   1) user_guide_src/source/libraries/uploaded_files/002.php (unary_operator_spaces, not_operator_with_successor_space, no_whitespace_in_blank_line)
      ---------- begin diff ----------
--- /home/runner/work/CodeIgniter4/CodeIgniter4/user_guide_src/source/libraries/uploaded_files/002.php
+++ /home/runner/work/CodeIgniter4/CodeIgniter4/user_guide_src/source/libraries/uploaded_files/002.php
@@ -29,7 +29,7 @@
         ];
 
         $postData = ['userfile' => $this->request->getPost('userfile')];
-        
+
         if (! $this->validateData($postData, $validationRule)) {
             $data = ['errors' => $this->validator->getErrors()];
 

      ----------- end diff -----------

https://github.com/codeigniter4/CodeIgniter4/actions/runs/7624518338/job/20791002149?pr=8445

[kenjis]

@stuart897 Could you tell me what prevented you from fixing the PR?

[stuart897]

@stuart897 Could you tell me what prevented you from fixing the PR?

Busy at work, the feedback seemed extremely minor & as it hadn't been merged in the meantime thought better to close.