Update syntax section (#364)
Update syntax section (#364)

* pick up from commit

NOTE:
  ref: https://github.com/vuejs/vuejs.org/commit/8f55bb0213c19bcd8d724849a57b2d6e37c1e47c

* translate prev commit

potato4d/jp.vuejs.org,vuejs/jp.vuejs.org,potato4d/jp.vuejs.org,vuejs/jp.vuejs.org