[docs] Add Meta information block

README.md

@@ -37,8 +37,8 @@ State management features:
 * **[Guarded](https://nsk90.github.io/kstatemachine/#guarded-transitions)
   and [Conditional transitions](https://nsk90.github.io/kstatemachine/#conditional-transitions)** - dynamic target
   state which is calculated in a moment of event processing depending on application business logic
-* **[Nested states](https://nsk90.github.io/kstatemachine/#nested-states)** - build hierarchical state machines (
-  statecharts)
+* **[Nested states](https://nsk90.github.io/kstatemachine/#nested-states)** - build hierarchical state machines
+  (statecharts)
   with [cross-level transitions](https://nsk90.github.io/kstatemachine/#cross-level-transitions) support
 * **[Composed (nested) state machines.](https://nsk90.github.io/kstatemachine/#composed-(nested)-state-machines)** Use
   state machines as atomic child states
@@ -71,8 +71,8 @@ State management features:
 stateDiagram-v2
     direction LR
     [*] --> GreenState
-    GreenState --> YellowState : SwitchEvent
-    YellowState --> RedState : SwitchEvent
+    GreenState --> YellowState: SwitchEvent
+    YellowState --> RedState: SwitchEvent
     RedState --> [*]
 
 ```

docs/index.md

@@ -36,6 +36,7 @@
 * [Optional arguments](#optional-arguments)
     * [Event argument](#event-argument)
     * [Transition argument](#transition-argument)
+* [Meta information](#meta-information)
 * [Error handling](#error-handling)
     * [Ignored events](#ignored-events)
     * [Pending events](#pending-events)
@@ -754,6 +755,17 @@ state("first") {
 > It is up to user to control that argument field is set from one listener. You can use some mutable data structure
 > and fill it from multiple listeners.
 
+## Meta information
+
+The library provides `metaInfo` property for `IState` and `Transition` types.
+`MetaInfo` is a marker interface allowing to attach some static information to library primitives.
+This mechanism is extendable and users may add their own `MetaInfo` sub interfaces/classes if necessary.
+Currently the only standard implementation is `UmlMetaInfo` which is useful for export feature.
+See [controlling export output](#controlling-export-output).
+
+> [!NOTE]
+> MetaInfo considered to be immutable data by design
+
 ## Error handling
 
 ### Ignored events