[TwigComponent][Doc] Remove false mention of PHP parsing

[smnandre]

Message on Slack:

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When i am using the array syntax described in the codeblock https://symfony.com/bundles/ux-twig-component/current/index.html#component-html-syntax

// pass object, array, or anything you imagine
<twig:Alert :foo="['col' => ['foo', 'oof']]" />

, i get following error:

An array element must be followed by a comma. Unexpected token "arrow function" of value "=>" ("punctuation" expected with value ",").

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We need to remove it from the documentation