fix server names [ci skip]

Per feedback in https://github.com/rails/rails/commit/af63e4a2546629c3fb2d53cffb7d4ea0e8663f68#commitcomment-7477636
fix grammar [ci skip]
Merge pull request #16604 from saarons/clean-remote-ip-middleware

ActionDispatch::RemoteIp accept IPAddr matches for trusted proxies
Revert "Add I18n support for `:placeholder` HTML option is passed to form fields"
Merge pull request #16629 from rails/revert-16438-input-placeholder-i18n

Revert "Add I18n support for `:placeholder` HTML option is passed to for...
[ci skip] Added documentation for has_and_belongs_to_many scope parameter
Merge pull request #16630 from tomkadwill/added_has_and_belongs_to_many_scope_documentation

[ci skip] Added documentation for has_and_belongs_to_many scope parameter
[ci skip] Running AR tests guide [Fixes GH-15891]

Patch by @bcjordan
Follow up on #16408

[skip ci]
Merge branch 'jonatack-patch-8'
add nested_model_forms to guides/documents.yaml [wip] [ci skip]
Merge pull request #11859 from zzak/nested_model_forms_guide

See AR::Associations for greater detail in Nested Model Forms Guide [ci skip]
Pass logging message through block.

This follows the good practice listed on http://guides.rubyonrails.org/debugging_rails_applications.html#impact-of-logs-on-performance
Missing space. [CI SKIP]
Merge pull request #16634 from tgxworld/missing_space

Missing space. [CI SKIP]
Merge pull request #16633 from tgxworld/prefer_log_message_through_block

Pass logging message through block.
Using `each_with_object` instead of `reduce`

This way no new object allocation is taking place. Thanks @jeremy for
the suggestion!
add I18n support for `:placeholder` HTML option is passed to form fields
just use the placeholder tag value if it is passed as a String
Merge pull request #16560 from robin850/rbx-duration-eql

Define the Duration#instance_of? method