document default context for the serializer

Author: dbu

reference/configuration/framework.rst

@@ -2752,6 +2752,9 @@ A map with default context options that will be used with each ``serialize`` and
 call. This can be used for example to set the json encoding behavior by setting ``json_encode_options``
 to a `json_encode flags bitmask`_.
 
+You can inspect the :ref:`serializer context builders <serializer-using-context-builders>`
+to discover the available settings.
+
 php_errors
 ~~~~~~~~~~
 

serializer.rst

@@ -130,14 +130,15 @@ configuration:
             serializer:
                 default_context:
                     enable_max_depth: true
+                    yaml_indentation: 2
 
     .. code-block:: xml
 
         <!-- config/packages/framework.xml -->
         <framework:config>
             <!-- ... -->
             <framework:serializer>
-                <default-context enable-max-depth="true"/>
+                <default-context enable-max-depth="true" yaml-indentation="2"/>
             </framework:serializer>
         </framework:config>
 
@@ -146,11 +147,13 @@ configuration:
         // config/packages/framework.php
         use Symfony\Config\FrameworkConfig;
         use Symfony\Component\Serializer\Normalizer\AbstractObjectNormalizer;
+        use Symfony\Component\Serializer\Encoder\YamlEncoder;
 
         return static function (FrameworkConfig $framework) {
             $framework->serializer()
                 ->defaultContext([
-                    AbstractObjectNormalizer::ENABLE_MAX_DEPTH => true
+                    AbstractObjectNormalizer::ENABLE_MAX_DEPTH => true,
+                    YamlEncoder::YAML_INDENTATION => 2,
                 ])
             ;
         };