[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

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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remove outdated docs

Fix FileStore#cleanup to no longer rely on missing each_key method

Enabled quirks mode on JSON.parse, fixes broken test in af9caae9

It turns out that ActionPack depends on the decoder to parse JSON
"fragments" (e.g. '"a string"', '1', 'null', etc), so we need to
enable quirks mode on JSON.parse. Also added coverage on the decoder
side to prevent regression.

[ci skip]