Removes unused code related to DatabaseTasks.

[ci skip] Consistency wording of 9.6 in form_helpers.md

Chapter 9 is giving a user and set of addresses example.
So 'Add a new address' would be more consistent.
Also change the javascript to JavaScript.

[ci skip] Update plugins.md

Highlighted code.

Removing ActiveSupport::Concern, it's not needed

Fixing comment typo in ActionController::Base

Before this commit options for `rails new` and `rails plugin new` had to
be passed in a strict order, trying to execute a following command:

    rails new -J path/to/app

resulted in an error.

This commit fixes the situation and allows to pass path to app anywhere
after `new`

Custom flash should be defined only for the class that defines it and it's subclasses

Fixes #12057

Update 3_2_release_notes.md

Fix typos: the indefinite articles(a -> an).

Fixed typo and applied proper code highlighting.

Deprecate the delegation of Array bang methods in ActiveRecord::Delegation

Conflicts:
	activerecord/CHANGELOG.md
	activerecord/test/cases/relation_test.rb

Make CollectionAssociation first/last with integer fetch with query

Conflicts:
	activerecord/CHANGELOG.md

[ci skip]

Let the SQLite rake tasks run without rails

Allow Relation#from to accept other relations with bind values.

Conflicts:
	activerecord/CHANGELOG.md

[ci skip]

do not break params filtering on nil values

Copy-edits

[ci skip]

[ci skip] Documentation on how to create custom rake tasks.

Remove unnecessary loop

"generates" applies to "collection radio" so it should be singular

I accidentally pushed this change to docrails before realizing that it's technically a code change, so I'm opening this pull request (and rolling back my change to docrails).

[ci skip]

form_for - fix :namespace and :as options clash

Conflicts:
	actionview/CHANGELOG.md

Removed semicolon and added space

[ci skip] Add missing setting locale code snippet.

This reverts commit ab5cd54b, reversing
changes made to cdc10c89.

Reason: This way of defining root path is still supported. See
https://github.com/rails/rails/blob/d262773ab7f0aae5de2d354ac2eca168e95b653d/actionpack/test/controller/routing_test.rb#L450-457

remove outdated docs