export_words.rb

files = Dir["./**/*"]

files.each do |file|
  next if File.directory?(file)
  
  words = []
  begin
    File.read(file).scan /[\u0400-\u04FF\-]+/ do |match|
      words << match
    end
  rescue # skip images, fonts, etc
  end
  
  if words.any?
    puts file, words.uniq.join(" ")
  end
end

# then go to http://api.yandex.ru/speller/ and check spelling