Fix sidekiq start text in documentation and gitlab:check

README.md

@@ -99,7 +99,7 @@ Start it with [Foreman](https://github.com/ddollar/foreman)
 or start each component separately
     bundle exec rails s
-    bundle exec rake sidekiq:start
+    script/background_jobs start
 ### Run the tests

lib/tasks/gitlab/check.rake

@@ -648,7 +648,7 @@ namespace :gitlab do
       else
         puts "no".red
         try_fixing_it(
-          sudo_gitlab("bundle exec rake sidekiq:start RAILS_ENV=production")
+          sudo_gitlab("RAILS_ENV=production script/background_jobs start")
         )
         for_more_information(
           see_installation_guide_section("Install Init Script"),