Document transient_local_cache_multiplier config (#342)

DEFAULT_CONFIG.json5

@@ -146,6 +146,15 @@
       //   }
       // },
 
+      //// transient_local_cache_multiplier: A multiplier used to determine the size of the `PublicationCache` for a route serving a `TRANSIENT_LOCAL` Publisher.
+      ////                                   When a `TRANSIENT_LOCAL` Publisher is discovered, the plugin creates a route with a `PublicationCache` to store
+      ////                                   the publications for late joiner bridges that serve late joiner Subscribers.
+      ////                                   The cache size must be at least equal to the Publisher's `history_length` QoS setting.
+      ////                                   Since the plugin creates one route per topic, the route might serve multiple Publishers.
+      ////                                   Therefore, the `PublicationCache` size is calculated as `history_length * transient_local_cache_multiplier`.
+      ////                                   If there are more than 10 `TRANSIENT_LOCAL` Publishers on the same topic, consider increasing this multiplier.
+      // transient_local_cache_multiplier: 10,
+
       ////
       //// This plugin uses Tokio (https://tokio.rs/) for asynchronous programming. 
       //// When running as a plugin within a Zenoh router, the plugin creates its own Runtime managing 2 pools of threads:
@@ -155,11 +164,11 @@
       //// When running as a standalone bridge the Zenoh Session's Runtime is used and can be configured via the
       //// `ZENOH_RUNTIME` environment variable. See https://docs.rs/zenoh-runtime/latest/zenoh_runtime/enum.ZRuntime.html
       ////
-      
+
       //// work_thread_num: The number of worker thread in the asynchronous runtime will use. (default: 2)
       ////                  Only for a plugin, no effect on a bridge.
       // work_thread_num: 2,
-      
+
       //// max_block_thread_num: The number of blocking thread in the asynchronous runtime will use. (default: 50)
       ////                       Only for a plugin, no effect on a bridge.
       // max_block_thread_num: 50,