message: fix(docs-infra): wrap the main aio mat-toolbar in a header
  wrap the main aio mat-toolbar in a header element to provide better
  accessibility
  resolves (the first point)
  PR Close
diff: <mat-progress-bar mode="indeterminate" color="warn"></mat-progress-bar>
  </div>
  +<header>
  <mat-toolbar color="primary" class="app-toolbar no-print" [class.transitioning]="isTransitioning">
  <mat-toolbar-row class="notification-container">
  <aio-notification notificationId="survey-january-2022" expirationDate="2022-02-01" [dismissOnContentClick]="true" (dismissed)="notificationDismissed()">
  </div>
  </mat-toolbar-row>
  </mat-toolbar>
  +</header>
  <aio-search-results #searchResultsView *ngIf="showSearchResults" [searchResults]="searchResults | async" (resultSelected)="hideSearchResults()"></aio-search-results>
  