Update deprecation-related config descriptions [ci-skip]

This updates the description of several deprecation-related
configuration settings to clarify that their "default" values are from
the default generated `config/environments` files, and that those values
vary by environment.  This also updates the description of the
`active_support.deprecation_behavior` initializer to mention the new
`Rails.application.deprecators`, and to link to the relevant
configuration settings.

Author: jonathanhefner

guides/source/configuring.md

@@ -2031,19 +2031,25 @@ The default value depends on the `config.load_defaults` target version:
 
 #### `config.active_support.deprecation`
 
-Configures the behavior of deprecation warnings. The options are `:raise`, `:stderr`, `:log`, `:notify`, or `:silence`. The default is `:stderr`.
+Configures the behavior of deprecation warnings. The options are `:raise`, `:stderr`, `:log`, `:notify`, and `:silence`.
+
+In the default generated `config/environments` files, this is set to `:log` for development and `:stderr` for test, and it is omitted for production in favor of [`config.active_support.report_deprecations`](#config-active-support-report-deprecations).
 
 #### `config.active_support.disallowed_deprecation`
 
-Configures the behavior of disallowed deprecation warnings. The options are `:raise`, `:stderr`, `:log`, `:notify`, or `:silence`. The default is `:raise`.
+Configures the behavior of disallowed deprecation warnings. The options are `:raise`, `:stderr`, `:log`, `:notify`, and `:silence`.
+
+In the default generated `config/environments` files, this is set to `:raise` for both development and test, and it is omitted for production in favor of [`config.active_support.report_deprecations`](#config-active-support-report-deprecations).
 
 #### `config.active_support.disallowed_deprecation_warnings`
 
 Configures deprecation warnings that the Application considers disallowed. This allows, for example, specific deprecations to be treated as hard failures.
 
 #### `config.active_support.report_deprecations`
 
-Allows you to disable all deprecation warnings (including disallowed deprecations); it makes `ActiveSupport::Deprecation.warn` a no-op. This is enabled by default in production.
+When `false`, disables all deprecation warnings, including disallowed deprecations, making `ActiveSupport::Deprecation.warn` a no-op.
+
+In the default generated `config/environments` files, this is set to `false` for production.
 
 #### `config.active_support.remove_deprecated_time_with_zone_name`
 
@@ -3042,7 +3048,7 @@ Below is a comprehensive list of all the initializers found in Rails in the orde
 
 * `i18n.callbacks`: In the development environment, sets up a `to_prepare` callback which will call `I18n.reload!` if any of the locales have changed since the last request. In production this callback will only run on the first request.
 
-* `active_support.deprecation_behavior`: Sets up deprecation reporting for environments, defaulting to `:log` for development, `:silence` for production, and `:stderr` for test.  Can be set to an array of values. This initializer also sets up behaviors for disallowed deprecations, defaulting to `:raise` for development and test and `:silence` for production. Disallowed deprecation warnings default to an empty array.
+* `active_support.deprecation_behavior`: Sets up deprecation reporting behavior for [`Rails.application.deprecators`][] based on [`config.active_support.report_deprecations`](#config-active-support-report-deprecations), [`config.active_support.deprecation`](#config-active-support-deprecation), [`config.active_support.disallowed_deprecation`](#config-active-support-disallowed-deprecation), and [`config.active_support.disallowed_deprecation_warnings`](#config-active-support-disallowed-deprecation-warnings).
 
 * `active_support.initialize_time_zone`: Sets the default time zone for the application based on the `config.time_zone` setting, which defaults to "UTC".
 
@@ -3133,6 +3139,8 @@ Below is a comprehensive list of all the initializers found in Rails in the orde
 
 * `disable_dependency_loading`: Disables the automatic dependency loading if the `config.eager_load` is set to `true`.
 
+[`Rails.application.deprecators`]: https://api.rubyonrails.org/classes/Rails/Application.html#method-i-deprecators
+
 Database Pooling
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