= bootstrap_form_for [:editor, @category], layout: :horizontal, label_col: 'col-sm-2', control_col: 'col-sm-10' do |f|
  = f.text_field :name
  = f.text_area :description, class: "markdown-editor", data: {upload_path: editor_images_url}
  = f.text_field :slug, help: "URLの一部に使うこのカテゴリを表すわかりやすい英単語を指定します"
  = f.collection_select :parent_id, current_site.categories, :id, :name, {include_blank: true}, {class: "select2", "data-select2-allow-clear": false}

  = f.form_group do
    = f.submit

= bootstrap_form_for [:editor, @category], layout: :horizontal, label_col: 'col-sm-2', control_col: 'col-sm-10' do |f|
  = f.text_field :name
  = f.text_area :description, class: "markdown-editor", data: {upload_path: editor_images_url}
  = f.text_field :slug, help: "URLの一部に使うこのカテゴリを表すわかりやすい英単語を指定します"
  - help_text = "親カテゴリを指定します。指定しない場合はトップレベルのカテゴリになります"
  = f.collection_select :parent_id, current_site.categories, :id, :name, {include_blank: true, help: help_text}, {class: "select2", "data-select2-allow-clear": true}

  = f.form_group do
    = f.submit

Add help text and change `data-select2-allow-clear` to true
Add help text and change `data-select2-allow-clear` to true
