minor #17399 [Session] Add docs to define redis session handler via php.ini directly (alexander-schranz)

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

Discussion
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[Session] Add docs to define redis session handler via php.ini directly

I think the most easiest way to configure session handling via redis is still configure it via `php.ini` and not via the Symfony Application.

Commits
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b29c212 [Session] Add docs to define redis session handler via php.ini directly

Author: javiereguiluz

session/database.rst

@@ -17,6 +17,17 @@ Store Sessions in a key-value Database (Redis)
 This section assumes that you have a fully-working Redis server and have also
 installed and configured the `phpredis extension`_.
 
+Via the redis extension it is possible to configure redis as a session handler
+directly in the servers ``php.ini`` file.
+
+.. code-block:: ini
+
+    ; php.ini
+    session.save_handler = redis
+    session.save_path = "tcp://192.168.0.178:6379?auth=REDIS_PASSWORD"
+
+Alternative you can configure it in the Symfony application.
+
 First, define a Symfony service for the connection to the Redis server:
 
 .. configuration-block::