message: chore: add NgOptionHighlightModule to stackblitz example
diff: @@ -2,6 +2,7 @@ import { Component, NgModule } from '@angular/core';
  import { BrowserModule } from '@angular/platform-browser';
  import { FormsModule, ReactiveFormsModule } from '@angular/forms';
  import { NgSelectModule } from '@ng-select/ng-select';
  +import { NgOptionHighlightModule } from '@ng-select/ng-option-highlight';
  import { CommonModule } from '@angular/common';
  import { HttpClientModule } from '@angular/common/http';
  @@ -18,6 +19,7 @@ export class AppComponent {}
  BrowserModule,
  FormsModule,
  NgSelectModule,
  + NgOptionHighlightModule,
  CommonModule,
  ReactiveFormsModule,
  HttpClientModule
  