minor symfony#54326 [Yaml] prefix examples with # (tacman)

This PR was squashed before being merged into the 7.0 branch.

Discussion
----------

[Yaml] prefix examples with #

| Q             | A
| ------------- | ---
| Branch?       | 7.0
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Issues        | Fix #symfony#54154
| License       | MIT

As mentioned in the issue, the yaml before wasn't valid, as the examples were dumped as an array in the yaml.  This simply comments the examples.

Commits
-------

fd95a8f [Yaml] prefix examples with #

Author: fabpot

src/Symfony/Component/Config/Definition/Dumper/YamlReferenceDumper.php

@@ -170,7 +170,7 @@ private function writeNode(NodeInterface $node, ?NodeInterface $parentNode = nul
 
             $this->writeLine('# '.$message.':', $depth * 4 + 4);
 
-            $this->writeArray(array_map(Inline::dump(...), $example), $depth + 1);
+            $this->writeArray(array_map(Inline::dump(...), $example), $depth + 1, true);
         }
 
         if ($children) {
@@ -191,7 +191,7 @@ private function writeLine(string $text, int $indent = 0): void
         $this->reference .= sprintf($format, $text)."\n";
     }
 
-    private function writeArray(array $array, int $depth): void
+    private function writeArray(array $array, int $depth, bool $asComment = false): void
     {
         $isIndexed = array_is_list($array);
 
@@ -201,11 +201,12 @@ private function writeArray(array $array, int $depth): void
             } else {
                 $val = $value;
             }
+            $prefix = $asComment ? '# ' : '';
 
             if ($isIndexed) {
-                $this->writeLine('- '.$val, $depth * 4);
+                $this->writeLine($prefix.'- '.$val, $depth * 4);
             } else {
-                $this->writeLine(sprintf('%-20s %s', $key.':', $val), $depth * 4);
+                $this->writeLine($prefix.sprintf('%-20s %s', $key.':', $val), $depth * 4);
             }
 
             if (\is_array($value)) {

src/Symfony/Component/Config/Tests/Definition/Dumper/YamlReferenceDumperTest.php

@@ -117,8 +117,8 @@ enum:                 ~ # One of "this"; "that"; Symfony\Component\Config\Tests\
     variable:
 
         # Examples:
-        - foo
-        - bar
+        # - foo
+        # - bar
     parameters:
 
         # Prototype: Parameter name