Merge branch '5.4' into 6.4

* 5.4:
  Clarify not using the Config component for app configuration
  Clarify the purpose of the Config component

best_practices.rst

@@ -109,6 +109,10 @@ Define these options as :ref:`parameters <configuration-parameters>` in the
 :ref:`environment <configuration-environments>` in the ``config/services_dev.yaml``
 and ``config/services_prod.yaml`` files.
 
+Unless the application configuration is reused multiple times and needs
+rigid validation, do *not* use the :doc:`Config component </components/config>`
+to define the options.
+
 Use Short and Prefixed Parameter Names
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

components/config.rst

@@ -1,9 +1,17 @@
 The Config Component
 ====================
 
-    The Config component provides several classes to help you find, load,
-    combine, fill and validate configuration values of any kind, whatever
-    their source may be (YAML, XML, INI files, or for instance a database).
+The Config component provides utilities to define and manage the configuration
+options of PHP applications. It allows you to:
+
+* Define a configuration structure, its validation rules, default values and documentation;
+* Support different configuration formats (YAML, XML, INI, etc.);
+* Merge multiple configurations from different sources into a single configuration.
+
+.. note::
+
+    You don't have to use this component to configure Symfony applications.
+    Instead, read the docs about :doc:`how to configure Symfony applications </configuration>`.
 
 Installation
 ------------