Removing a repetitive comment and removing a deprecation warning.

The comment on the +env_config+ method is repetitive, likely to get
outdated, and provides no useful information which cannot be gleamed
from the code. I'm therefore removing it. I'm also refactoring the check
for the presence of a secret_token in the configuration.
Merge pull request #10986 from wangjohn/changing_rails_env_config

Removing a repetitive comment and a deprecation warning.
`CollectionProxy#include?` returns `true` and `false` as documented.
Merge pull request #10987 from senny/10979_association_include_returns_true

`CollectionProxy#include?` returns `true` and `false` as documented.
Add `respond_with` `location` option to the docs
Merge pull request #10988 from tute/master

Add respond_with location option to docs Edit
It takes 4 spaces or some backticks to have this code displayed as code in the changelog.
Fix formatting of my name in the changelog, and given Aaron credit for b483a0d2a75b
Merge pull request #10998 from Empact/tidy-changelog

Fix some activerecord changelog code to be displayed properly as code [ci skip]
do not load all child records for inverse case

currently `post.comments.find(Comment.first.id)` would load all
comments for the given post to set the inverse association.

This has a huge performance penalty. Because if post has 100k
records and all these 100k records would be loaded in memory
even though the comment id was supplied.

Fix is to use in-memory records only if loaded? is true. Otherwise
load the records using full sql.

Fixes #10509
Merge pull request #10566 from neerajdotname/10509d

do not load all child records for inverse case
Fixed ActiveModel::Model's inclusion chain
Merge pull request #11002 from fredwu/master-activemodel-inclusion-chain-fix

Fixed ActiveModel::Model's inclusion chain
Remove duplicate letter 'a'. [ci skip]
Merge pull request #11007 from ugisozols/remove_duplicate_letter

Remove duplicate letter 'a'. [ci skip]
better documentation for `AS::Testing::Declarative#test`. [ci skip]
log the sql that is actually sent to the database

If I have a query that produces sql
`WHERE "users"."name" = 'a         b'` then in the log all the
whitespace is being squeezed. So the sql that is printed in the
log is `WHERE "users"."name" = 'a b'`.

This can be confusing. This commit fixes it by ensuring that
whitespace is not squeezed.

fixes #10982
Merge pull request #10991 from neerajdotname/10982

log the sql that is actually sent to the database
add documentation for `ActiveSupport::Testing::SetupAndTeardown`.
Revert "Merge pull request #10566 from neerajdotname/10509d"

This reverts commit 2b817a5e89ac0e7aeb894a40ae7151a0cf3cef16, reversing
changes made to 353a398bee68c5ea99d76ac7601de0a5fef6f4a5.

Conflicts:
	activerecord/CHANGELOG.md

Reason: the build broke