Add back sqlite plugin database config option

roles/matrix-bot-maubot/templates/config/config.yaml.j2

@@ -27,6 +27,9 @@ plugin_directories:
 
 # Configuration for storing plugin databases
 plugin_databases:
+  # Some plugins still require sqlite, so configure a path here.
+  # postgres will be used if supported.
+  sqlite: /data/dbs
   postgres: default
 
 server: