Merge pull request rails#20736 from antoine-lizee/docs

[ci skip] docs: making clear that perform_caching has a limited impact

Author: robin850

actionpack/lib/action_controller/caching.rb

@@ -8,7 +8,7 @@ module ActionController
   #
   # You can read more about each approach by clicking the modules below.
   #
-  # Note: To turn off all caching, set
+  # Note: To turn off all caching provided by Action Controller, set
   #   config.action_controller.perform_caching = false
   #
   # == \Caching stores

guides/source/caching_with_rails.md

@@ -31,6 +31,11 @@ the relevant `config/environments/*.rb` file:
 config.action_controller.perform_caching = true
 ```
 
+NOTE: Changing the value of `config.action_controller.perform_caching` will
+only have an effect on the caching provided by the Action Controller component. 
+For instance, it will not impact low-level caching, that we address
+[below](#low-level-caching).
+
 ### Page Caching
 
 Page caching is a Rails mechanism which allows the request for a generated page

guides/source/configuring.md

@@ -326,7 +326,7 @@ The schema dumper adds one additional configuration option:
 
 * `config.action_controller.asset_host` sets the host for the assets. Useful when CDNs are used for hosting assets rather than the application server itself.
 
-* `config.action_controller.perform_caching` configures whether the application should perform caching or not. Set to false in development mode, true in production.
+* `config.action_controller.perform_caching` configures whether the application should perform the caching features provided by the Action Controller component or not. Set to false in development mode, true in production.
 
 * `config.action_controller.default_static_extension` configures the extension used for cached pages. Defaults to `.html`.