docs(spindle-ui): ButtonのDesign DocにContained/Outlined並び順ガイドラインを追加

[MasatoHonda]

縦並び・横並び時のContainedボタンとOutlinedボタンの配置ルールを
スクリーンショットとDO/DO NOTに追記した。

[changeset-bot]

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Latest commit: 5c22469

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