README: update

Author: Garefild

README.md

@@ -8,18 +8,21 @@ management using Redux.
 [![downloads per month](https://img.shields.io/npm/dm/@angular-redux2/undo.svg)](https://www.npmjs.com/package/@angular-redux2/undo)
 
 ## Installation
+
 You can install angular-redux2/sync using npm:
 
 ```bash
 npm install @angular-redux2/undo
 ```
 
 ## Usage
-- Take me to the [API docs](https://angular-redux2.github.io/undo).
+
+> Take me to the [API docs](https://angular-redux2.github.io/undo).
 
 To use `@angular-redux2/undo` in your Angular application, follow these steps:
 Define a StateWatchMap object that maps the properties you want to track for undo/redo operations to their corresponding
-state paths and configure the undo middleware in your Angular-Redux2/store setup by including it in the list of middleware:
+state paths and configure the undo middleware in your Angular-Redux2/store setup by including it in the list of
+middleware:
 
 ```typescript
 const middleware: Array<Middleware> = [
@@ -28,15 +31,26 @@ const middleware: Array<Middleware> = [
             path: 'path.to.property1'
         },
         propertyName2: {
-            path: 'path.to.property2'
+            path: 'path.to.property2',
+            limit: 5
         },
     }),
 ];
 
 ngRedux.configureStore(rootReducer, {}, middleware, enhancer);
 ```
+
+settings:
+
+- `path` (required): The path to the property in the state object using dot notation.
+- `filter` (optional): A filter function that determines if the property should be watched for undo/redo. Return true to
+  include the property, and false to exclude it. If not specified, all properties are included.
+- `limit` (optional): The maximum number of past snapshots to keep in the undo history. If the limit is reached, the
+  oldest snapshots are discarded. If not specified, no limit is applied.
+
 Implement the undo/redo functionality in your Angular component or service.
-You can use the `undo`, `redo`, `jump`, and `clear_history` methods provided by `NgUndoStateActions` to perform the corresponding actions:
+You can use the `undo`, `redo`, `jump`, and `clear_history` methods provided by `NgUndoStateActions` to perform the
+corresponding actions:
 
 ```typescript
 // Example component
@@ -54,7 +68,8 @@ import { undo, redo, jump, clear_history } from '@angular-redux2/undo';
   `
 })
 export class ExampleComponent {
-    constructor(private undoStateActions: NgUndoStateActions) {}
+    constructor(private undoStateActions: NgUndoStateActions) {
+    }
 
     @Dispatch
     onUndo() {
@@ -77,3 +92,47 @@ export class ExampleComponent {
     }
 }
 ```
+
+## State Watch Map
+
+The state watch map is an object that defines the paths to the state properties you want to track for undo. It has the
+following structure:
+
+```typescript
+export interface StateWatchMap {
+    [key: string]: {
+        path: string;
+        filter?: (action: any, currentState: any, snapshot: any) => boolean;
+        limit?: number;
+    }
+}
+```
+
+- `key` (string): The unique identifier for the state property.
+- `path` (string): The dot-separated path to the state property.
+- `filter` (optional function): A filter function that determines if an action should be captured in the undo history
+  for the specific state property.
+
+## Custom Filters
+
+You can define custom filter functions to control which actions are captured in the undo history for each state
+property.
+The filter function takes three parameters:
+
+- `action`: The dispatched action object.
+- `currentState`: The current store state object.
+- `snapshot`: The snapshot to insert into the history.
+
+The filter function should return true if the action should be captured, or false otherwise.
+Here's an example of a custom filter function that only captures actions with specific types:
+
+```typescript
+const stateWatchMap: StateWatchMap = {
+    'todos': {
+        path: 'todos',
+        filter: (action: any, currentState: any, snapshot: any): boolean => {
+            return action.type === 'ADD_TODO' || action.type === 'REMOVE_TODO';
+        }
+    }
+};
+```