Add readme note

Author: Shatur

README.md

@@ -15,6 +15,7 @@ If you are new to networking, see [glossary](https://gist.github.com/maniwani/f9
 - Automatic world replication.
 - Remote events and triggers.
 - Control over client visibility of entities and events.
+- Specify which entities should be replicated in sync using ECS relationships.
 - Replication into scene to save server state.
 - Customizable serialization and deserialization even for types that don't implement `serde` traits (like `Box<dyn Reflect>`).
 - Abstracts game logic to support singleplayer, client, dedicated server, and listen server configurations simultaneously.