minor symfony#12325 Reworded the docs about storing sessions in database (javiereguiluz)

This PR was squashed before being merged into the 4.4 branch.

Discussion
----------

Reworded the docs about storing sessions in database

This is part of our ongoing effort to reword all Doctrine related docs.

I'll summon the power of the Symfony community to review this:

* @dkarlovi could you please review that the section about RedisSessionHandler is correct? Thanks!
* @stof could you please review the section about relational databases? Related to symfony#12324. Thanks!
* @alcaeus could you please review the section about MongoDB? I have some problems about the config needed to pass the MongoDB connection to MongoDBSessionHandler. Thanks!

The file to review is the new file `session/database.rst`. Here's how it looks rendered: https://github.com/javiereguiluz/symfony-docs/blob/b2ef983b79110cff8f85abeeffe78aa18f6bf31a/session/database.rst

Thank you all!

Commits
-------

500d961 Reworded the docs about storing sessions in database

Author: javiereguiluz

_build/redirection_map

@@ -479,3 +479,5 @@
 /components/translation/custom_formats https://github.com/symfony/translation
 /components/translation/custom_message_formatter https://github.com/symfony/translation
 /components/routing https://github.com/symfony/routing
+/doctrine/pdo_session_storage /session/database
+/doctrine/mongodb_session_storage /session/database

doctrine.rst

@@ -853,10 +853,9 @@ Learn more
     doctrine/custom_dql_functions
     doctrine/dbal
     doctrine/multiple_entity_managers
-    doctrine/pdo_session_storage
-    doctrine/mongodb_session_storage
     doctrine/resolve_target_entity
     doctrine/reverse_engineering
+    session/database
     testing/database
 
 .. _`Doctrine`: https://www.doctrine-project.org/

doctrine/mongodb_session_storage.rst

@@ -1233,70 +1233,17 @@ The service id used for session storage. The ``session.storage`` service
 alias will be set to this service id. This class has to implement
 :class:`Symfony\\Component\\HttpFoundation\\Session\\Storage\\SessionStorageInterface`.
 
+.. _config-framework-session-handler-id:
+
 handler_id
 ..........
 
 **type**: ``string`` **default**: ``null``
 
 The service id used for session storage. The default ``null`` value means to use
 the native PHP session mechanism. Set it to ``'session.handler.native_file'`` to
-let Symfony manage the sessions itself using files to store the session
-metadata.
-
-You can also configure the session handler with a DSN. For example:
-
-.. configuration-block::
-
-    .. code-block:: yaml
-
-        # config/packages/framework.yaml
-        framework:
-            session:
-                # ...
-                handler_id: 'redis://localhost'
-                handler_id: '%env(REDIS_URL)%'
-                handler_id: '%env(resolve:DATABASE_URL)%'
-                handler_id: 'file://%kernel.project_dir%/var/sessions'
-
-    .. code-block:: xml
-
-        <!-- config/packages/framework.xml -->
-        <?xml version="1.0" encoding="UTF-8" ?>
-        <container xmlns="http://symfony.com/schema/dic/services"
-            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-            xmlns:framework="http://symfony.com/schema/dic/symfony"
-            xsi:schemaLocation="http://symfony.com/schema/dic/services
-                https://symfony.com/schema/dic/services/services-1.0.xsd
-                http://symfony.com/schema/dic/symfony https://symfony.com/schema/dic/symfony/symfony-1.0.xsd">
-
-            <framework:config>
-                <framework:session enabled="true"
-                    handler-id="redis://localhost"
-                    handler-id="%env(REDIS_URL)%"
-                    handler-id="%env(resolve:DATABASE_URL)%"
-                    handler-id="file://%kernel.project_dir%/var/sessions"/>
-            </framework:config>
-        </container>
-
-    .. code-block:: php
-
-        // config/packages/framework.php
-        $container->loadFromExtension('framework', [
-            'session' => [
-                // ...
-                'handler_id' => 'redis://localhost',
-                'handler_id' => '%env(REDIS_URL)%',
-                'handler_id' => '%env(resolve:DATABASE_URL)%',
-                'handler_id' => 'file://%kernel.project_dir%/var/sessions',
-            ],
-        ]);
-
-.. versionadded:: 4.4
-
-    The option to configure the session handler with a DSN was introduced in Symfony 4.4.
-
-If you prefer to make Symfony store sessions in a database read
-:doc:`/doctrine/pdo_session_storage`.
+let Symfony manage the sessions itself using files to store the session metadata.
+You can also :doc:`store sessions in a database </session/database>`.
 
 .. _name:
 

doctrine/pdo_session_storage.rst

@@ -121,9 +121,8 @@ session metadata files:
         ]);
 
 Check out the Symfony config reference to learn more about the other available
-:ref:`Session configuration options <config-framework-session>`. Also, if you
-prefer to store session metadata in a database instead of the filesystem,
-check out this article: :doc:`/doctrine/pdo_session_storage`.
+:ref:`Session configuration options <config-framework-session>`. You can also
+:doc:`store sessions in a database </session/database>`.
 
 Basic Usage
 -----------
@@ -219,7 +218,9 @@ More about Sessions
 .. toctree::
     :maxdepth: 1
 
-    /doctrine/pdo_session_storage
+    session/sessions_directory
+    session/avoid_session_start
+    session/database
     session/locale_sticky_session
     session/php_bridge
     session/proxy_examples