Improve documentation about custom buttons.

Now it is not clear from documentation how to add custom buttons to implement some behavior with state manipulations. For example: how can we implement undo, redo buttons?

Now I’m using this code(not an expert in angular)

 @ViewChild('ngx', {static: false})
    ngx: NgxWigComponent;
    @Input()
    content = 'sss';
    inputStates: string[] = [];
    undoStats = 0;
    ngAfterViewInit(): void {
      this.ngx.toolbarButtons.push({
          label: 'Undo',
          title: 'Undo',
          command: (ctx: NgxWigComponent) => {
            this.undo();
          },
          styleClass: 'nw-button',
          icon: 'icon-custom'
        });
      this.ngx.toolbarButtons.push({
          label: 'Redo',
          title: 'Redo',
          command: (ctx: NgxWigComponent) => {
            this.redo();
          },
          styleClass: 'nw-button',
          icon: 'icon-custom'
        });
  }

[MPapini91]

Ah, for the command you can pass a function or a command from this list

[MPapini91]

Not just something to undo-redo editing? I tryed in https://stackblitz.com/edit/ngx-wig-sample-plugins?file=src/app.ts adding this after edithtml undo: { label: 'Undo', title: 'Undo', command: 'undo', styleClass: 'nw-button', }, redo: { label: 'Redo', title: 'Redo', command: 'redo', styleClass: 'nw-button' }