better clarity of params source in ActionController::Base documentation

change AR clear order in ActionDisplatch::Reloader hook

Change the `index` arg of `ActionDispatch::Static#new` to a kwarg

refactor ActiveRecord's #become by removing not needed code

This reverts commit 67e467b9.

Grammar correction

This reverts commit 3d949f34.

This was already documented in other PR.

Another use block variable instead of global

 Remove NOTE related to format.js [ci skip]

 - The example for which this NOTE was written was removed in
   https://github.com/rails/rails/pull/20493.

Removed AJAX example with poor convention adherence

The removed section promotes putting JS code directly inside the controller, this is not in line with convention.

Fix crash when loading fixture with belongs_to association defined in abstract base class

update Rails Command Line guide page

Fix typo in AM I18n validation test name

Use block variable instead of global