demo_app/my_platform/db/migrate/20151120091850_change_issues_description_to_text.your_platform.rb
# This migration comes from your_platform (originally 20151120071318)
class ChangeIssuesDescriptionToText < ActiveRecord::Migration[4.2]
def change
change_table :issues do |t|
t.change :description, :text
end
end
end