Generate sample config

docs/sample_config.yaml

@@ -1043,6 +1043,39 @@ media_store_path: "DATADIR/media_store"
 #    height: 600
 #    method: scale
 
+# Configure media retention settings. Media will be purged if it
+# has not been accessed in at least this amount of time. If the
+# media has never been access, the media's creation time is used
+# instead. Both thumbnails and the original media will be removed.
+#
+# Media is 'accessed' when loaded in a room in a client, or
+# otherwise downloaded by a local or remote user.
+#
+media_retention:
+    # Whether media retention settings should apply. Defaults to
+    # false.
+    #
+    # Uncomment to enable media retention on this homeserver.
+    #
+    #enabled: true
+
+    # How long to keep local media since its last access. Local
+    # media that is removed will be permanently deleted.
+    #
+    # If this option is not set, local media will not have a
+    # retention policy applied.
+    #
+    #local_media_lifetime: 30d
+
+    # How long to keep downloaded remote media since its last
+    # access. Remote media will be downloaded again from the
+    # originating server on demand.
+    #
+    # If this option is not set, remote media will not have a
+    # retention policy applied.
+    #
+    remote_media_lifetime: 7d
+
 # Is the preview URL API enabled?
 #
 # 'false' by default: uncomment the following to enable it (and specify a