Remove `rake initializers` from rake tasks list

Context https://github.com/rails/rails/pull/33631#discussion_r210732565

railties/lib/rails/tasks/initializers.rake

@@ -3,7 +3,6 @@
 require "rails/command"
 require "active_support/deprecation"
 
-desc "Print out all defined initializers in the order they are invoked by Rails."
 task :initializers do
   ActiveSupport::Deprecation.warn("Using `bin/rake initializers` is deprecated and will be removed in Rails 6.1. Use `bin/rails initializers` instead.\n")
   Rails::Command.invoke "initializers"