add description above for each task.

lib/whenever/job.rb

@@ -2,14 +2,15 @@
 
 module Whenever
   class Job
-    attr_reader :at, :roles
+    attr_reader :at, :roles, :description
 
     def initialize(options = {})
       @options = options
       @at                               = options.delete(:at)
       @template                         = options.delete(:template)
       @job_template                     = options.delete(:job_template) || ":job"
       @roles                            = Array(options.delete(:roles))
+      @description                      = options.delete(:description)
       @options[:output]                 = options.has_key?(:output) ? Whenever::Output::Redirection.new(options[:output]).to_s : ''
       @options[:environment_variable] ||= "RAILS_ENV"
       @options[:environment]          ||= :production

lib/whenever/job_list.rb

@@ -138,6 +138,7 @@ def cron_jobs
             job.has_role?(r)
           end
           Whenever::Output::Cron.output(time, job) do |cron|
+            cron.prepend "##{job.description}\n" unless job.description.to_s.empty?
             cron << "\n\n"
 
             if cron[0,1] == "@"