message: docs: move ZippyToggleDirective
  Move ZippyToggleDirective from app.component.ts
  PR Close
diff: -import { Component, Directive, Input, TemplateRef, ContentChild} from '@angular/core';
  +import { Component, Directive, Input, TemplateRef, ContentChild, HostBinding, HostListener } from '@angular/core';
  +
  +@Directive({
  + selector: 'button[appExampleZippyToggle]',
  +})
  +export class ZippyToggleDirective {
  + @HostBinding('attr.aria-expanded') ariaExpanded = this.zippy.expanded;
  + @HostBinding('attr.aria-controls') ariaControls = this.zippy.contentId;
  + @HostListener('click') toggleZippy() {
  + this.zippy.expanded = !this.zippy.expanded;
  + }
  + constructor(public zippy: ZippyComponent) {}
  +}
  let nextId = 0;
  