Document use with standalone-migrations

[dmolesUC]

Just FYI, I was able to use this gem outside of Rails with standalone-migrations, although I had to jump through a few hoops to create my own Rake task and make my model classes available to it. In case you want to document it (or in case anyone is looking for it in the issues), here's the relevant part of my Rakefile:

$LOAD_PATH.unshift(File.expand_path('app/models', __dir__))
Dir.glob(File.expand_path('app/models/*.rb', __dir__)).sort.each(&method(:require))
require 'seed_dump'

namespace :db do
  namespace :seed  do
    desc "Dump records from the database into db/seeds.rb"
    task :dump => :environment do
      SeedDump.dump_using_environment(ENV)
    end
  end
end