Ajout des configurations spécifiques du serveur Synapse (#302)

Sous la forme d'un bloc de code dans un premier temps pour plus de facilité.

services/matrix.md

@@ -160,6 +160,69 @@ est l'administrateur système du serveur (`@n-peugnet:club1.fr`),
 normalement, il n'a pas que ça à faire de vous espionner,
 mais si vous n'avez pas confiance en lui, il ne vous reste plus qu'à activer le chiffrement des conversations.
 
+Configurations spécifiques
+--------------------------
+
+Le serveur CLUB1 a des [ressources limitées](../info/infrastructure-materielle.md#serveur),
+il ne peut donc pas accueillir et conserver toutes les discussions à l'infini.
+Nous avons ainsi configuré {logiciel}`Synapse` en conséquence :
+
+```yaml
+# Message retention policy at the server level.
+#
+# Room admins and mods can define a retention period for their rooms using the
+# 'm.room.retention' state event, and server admins can cap this period by setting
+# the 'allowed_lifetime_min' and 'allowed_lifetime_max' config options.
+#
+# If this feature is enabled, Synapse will regularly look for and purge events
+# which are older than the room's maximum retention period. Synapse will also
+# filter events received over federation so that events that should have been
+# purged are ignored and not stored again.
+#
+retention:
+  # The message retention policies feature is disabled by default. Uncomment the
+  # following line to enable it.
+  #
+  enabled: true
+
+  # Default retention policy. If set, Synapse will apply it to rooms that lack the
+  # 'm.room.retention' state event. Currently, the value of 'min_lifetime' doesn't
+  # matter much because Synapse doesn't take it into account yet.
+  #
+  default_policy:
+    min_lifetime: 1d
+    max_lifetime: 3y
+
+media_retention:
+  local_media_lifetime: 2y
+  remote_media_lifetime: 90d
+
+# How long to keep locally forgotten rooms before purging them from the DB.
+# Defaults to null, meaning it's disabled.
+forgotten_room_retention_period: 20d
+
+# When this option is enabled, the room "complexity" will be checked before a user
+# joins a new remote room. If it is above the complexity limit, the server will
+# disallow joining, or will instantly leave.
+limit_remote_rooms:
+  enabled: true
+  complexity: 10
+  complexity_error: "Désolé, cette room est trop complèxe pour le serveur CLUB1."
+  admins_can_join: false
+
+# disable presence completely
+presence:
+  enabled: false
+
+# Rate limiting federation
+rc_federation:
+  # window_size: 1000 # default
+  sleep_limit: 5
+  # sleep_delay: 500 # default
+  reject_limit: 40
+  concurrent: 2
+```
+
 Logiciels
 ---------