improve component naiming docs
improve component naiming docs

NOTE:
  pick up from https://github.com/vuejs/vuejs.org/commit/e784916e4fd499e6c6b1ca067c95242ab401a51c

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