Add info about client-optional components

Author: Pyrofab

public/wiki/cardinal-components-api/modules/world.md

@@ -6,6 +6,13 @@ breadcrumb: Worlds
 
 This module allows mods to attach components to `World` objects. World components can be automatically synchronized by implementing `SyncedComponent`, most commonly through the `WorldSyncedComponent` helper interface.
 
+### A note about access
+
+World objects are among the easiest to access in your code (notably available on the client through `MinecraftClient#world` and on the server
+through `MinecraftServer#getWorld`), with the caveat that a client cannot retrieve data for a `World` that they are not currently in.
+If you need your clients to be aware of the custom data for another dimension (<i>e.g.</i> for fancy portal effects), you may be interested
+in a global data store like [Cardinal Components Scoreboard](./scoreboard).
+
 ## Usage
 ### Registration
 World components are registered by a [`WorldComponentInitializer`](https://github.com/Ladysnake/Cardinal-Components-API/blob/master/cardinal-components-world/src/main/java/org/ladysnake/cca/api/v3/world/WorldComponentInitializer.java), exposed as `cardinal-components-world` in the mod json (more information on the [component registration page](../registration#2-attaching-your-component)). Once a component factory is registered, its associated component will be available on every `World` instance, on both clients and servers.

public/wiki/cardinal-components-api/synchronization.md

@@ -28,7 +28,10 @@ public class SyncedIntComponent implements IntComponent, AutoSyncedComponent {
     // getters, setters, and serialization methods omitted for brevity
 }
 ```
-With that, all the data that you save through your serialization methods gets automatically synchronized whenever a player starts tracking the provider to which your component is attached. If your component has its value set during initialization and never changes, this would *technically* be enough. However, most components store *dynamic* values, which means you need to notify players of your changes. For that, all you need to do is call [`ComponentKey#sync`](https://github.com/Ladysnake/Cardinal-Components-API/blob/master/cardinal-components-base/src/main/java/org/ladysnake/cca/api/v3/component/ComponentKey.java#L110) whenever you update your component.
+With that, all the data that you save through your serialization methods gets automatically synchronized whenever a player starts tracking the provider to which your component is attached.
+If your component has its value set during initialization and never changes, this would *technically* be enough.
+However, most components store *dynamic* values, which means you need to notify players of your changes.
+For that, all you need to do is call [`ComponentKey#sync`](https://github.com/Ladysnake/Cardinal-Components-API/blob/master/cardinal-components-base/src/main/java/org/ladysnake/cca/api/v3/component/ComponentKey.java#L110) whenever you update your component.
 
 *For information on how to obtain a `ComponentKey`, refer to the [Registering and using a component](registration) page.*
 
@@ -129,4 +132,25 @@ public class SyncedIntComponent implements IntComponent, AutoSyncedComponent {
         }
     }
 }
-```
+```
+
+## Client-optional components
+
+Since Cardinal Components API 6.0, **attempting to sync a component to a player who does not have your mod installed clientside
+will now result in a disconnection.**
+
+If the client is missing Cardinal Components API, they will receive a message saying "This server requires Cardinal Components API".
+
+To disable this behaviour, you can override the `isRequiredOnClient` method in your `PlayerSyncPredicate` (typically your `AutoSyncComponent` implementation).
+For example:
+
+```java
+public class MyClientOptionalComponent implements AutoSyncedComponent {
+    @Override
+    public boolean isRequiredOnClient() {
+        return false;
+    }
+
+    // ...
+}
+```