Merge branch 'master' into preload

* master: (62 commits)
  Getting Started Guide: Hello Rails! -> Hello, Rails! and wrap code tag
  Add CHANGELOG entry for #12344
  Add regression test to #12343
  Fix typo in number_to_human docs: you -> your
  [Documentation] Add a missing validation to I18n docs
  Use the given name in html_options for the hidden field in collection_check_boxes
  assign_attributes should return if argument is blank.
  No need the else clause
  Use join to concat the both side of the AST
  Add a CHANGELOG entry about Web Console inclusion
  added column type to example in section 2.3
  Include web-console in new projects Gemfile
  ActiveRecord::ConnectionAdapters::Column.string_to_time method respects string with timezone. Closes #12278.
  add test_scoped_root_as_name
  Getting Started Guide: update RubyGems Guides link [ci skip]
  Deprecate unused quoted_locking_column method.
  Update references to wycats/thor to erikhuda/thor.
  bcrypt-ruby v3.1.2 supports Ruby 2.0 on Windows
  Fix the model name in the association basics guides
  We shouldn't override PostgreSQLAdapter's superclass inheritance while monkeypatching
  ...

1 files changed, 2 insertions, 1 deletions

diff --git a/guides/source/migrations.md b/guides/source/migrations.md
index 3c512e0390..0f5379059e 100644
--- a/guides/source/migrations.md
+++ b/guides/source/migrations.md
@@ -301,6 +301,7 @@ braces. You can use the following modifiers:
 * `precision`    Defines the precision for the `decimal` fields
 * `scale`        Defines the scale for the `decimal` fields
 * `polymorphic`  Adds a `type` column for `belongs_to` associations
+* `null`         Allows or disallows `NULL` values in the column.
 
 For instance, running
 
@@ -313,7 +314,7 @@ will produce a migration that looks like this
 ```ruby
 class AddDetailsToProducts < ActiveRecord::Migration
   def change
-    add_column :products, :price, precision: 5, scale: 2
+    add_column :products, :price, :decimal, precision: 5, scale: 2
     add_reference :products, :supplier, polymorphic: true, index: true
   end
 end