A warning line should look like a warning section

[ci skip]
Cleanup loaded features and constants after dependency tests.
Add a note on custom validation contexts.

The documentation on `:on` for validations was inconsistent, and most
only referenced the `:create` and `:update` contexts. I fixed those to
be consistent with the documentation on `AM::Validations.validates`,
which seemed to have the best docs.

[ci skip]
[ci skip] add guide for ActiveModel::SecurePassword
'Reversible' ->active_record_migrations [ci skip]

Reversible method documentation moved from migrations.md  to active_record_migrations.md
'Revert' ->active_record_migrations [ci skip]

Revert method documentation moved from migrations.md  to active_record_migrations.md
[ci skip] Fix some typos, normalize sentence.

Follow up of #16722.

https://github.com/rails/rails/pull/16722

also normalize all instance gained methods’ sentence.
form_helpers: demonstrating there is also a collection_select method in form builder
[ci skip] Fix code snippet display in Action Mailer Basics guide.
Consistently capitalize ETag.
Consistently markup etag options.
Explicit route test class

shows the class that the test must extend in order to have the assert_routing method available
Remove --skip-action-view option from application generator
Merge pull request #17042 from DanOlson/remove-skip-action-view

Remove --skip-action-view option from application generator
Fix typo
Merge pull request #17051 from jwworth/task/fix_typo

Fix typo
[ci skip] Add Doc of with_options for the case when inherited default options and original options have same keys
Use released rails-dom-testing
Use release web-console
Remove internal options from query string of paths

Fixes #17057