rake initializer -> rake initializers

Also edited the copy to be more consistent with `rake routes`.

See #19323.

railties/CHANGELOG.md

@@ -5,10 +5,11 @@
 
     *arthurnn*
 
-*   Add `rake initializer`
+*   Add `rake initializers`
 
-    This task prints out initializers for an application. It is useful to
-    develop a rubygem which involves the initialization process.
+    This task prints out all defined initializers in the order they are invoked
+    by Rails. This is helpful for debugging issues related to the initialization
+    process.
 
     *Naoto Kaneko*
 

railties/lib/rails/tasks.rb

@@ -4,7 +4,7 @@ require 'rake'
 %w(
   annotations
   framework
-  initializer
+  initializers
   log
   middleware
   misc

railties/lib/rails/tasks/initializers.rake

@@ -1,4 +1,4 @@
-desc "Prints out initializers for your application"
+desc "Print out all defined initializers in the order they are invoked by Rails."
 task initializer: :environment do
   Rails.application.initializers.tsort_each do |initializer|
     puts initializer.name