docs: add tree examples to documentation items

Author: tinayuangao

src/app/shared/documentation-items/documentation-items.ts

@@ -173,6 +173,13 @@ const DOCS: {[key: string]: DocCategory[]} = {
           'table-overview',
         ]},
       ]
+    },
+    {
+      id: 'trees',
+      name: 'Tree',
+      items: [
+        {id: 'tree', name: 'Tree', examples: ['tree-checklist', 'tree-dynamic', 'tree-loadmore']},
+      ]
     }
   ],
   [CDK] : [
@@ -195,7 +202,7 @@ const DOCS: {[key: string]: DocCategory[]} = {
       items: [
         {id: 'stepper', name: 'Stepper', examples: []},
         {id: 'table', name: 'Table', examples: []},
-
+        {id: 'tree', name: 'Tree', examples: []}
       ]
     },
     // TODO(jelbourn): re-add utilities and a11y as top-level categories once we can generate

src/assets/stackblitz/main.ts

@@ -1,6 +1,7 @@
 import './polyfills';
 
 import {CdkTableModule} from '@angular/cdk/table';
+import {CdkTreeModule} from '@angular/cdk/tree';
 import {HttpClientModule} from '@angular/common/http';
 import {NgModule} from '@angular/core';
 import {FormsModule, ReactiveFormsModule} from '@angular/forms';
@@ -38,6 +39,7 @@ import {
   MatTabsModule,
   MatToolbarModule,
   MatTooltipModule,
+  MatTreeModule,
 } from '@angular/material';
 import {BrowserModule} from '@angular/platform-browser';
 import {platformBrowserDynamic} from '@angular/platform-browser-dynamic';
@@ -47,6 +49,7 @@ import {MaterialDocsExample} from './app/material-docs-example';
 @NgModule({
   exports: [
     CdkTableModule,
+    CdkTreeModule,
     MatAutocompleteModule,
     MatButtonModule,
     MatButtonToggleModule,
@@ -79,6 +82,7 @@ import {MaterialDocsExample} from './app/material-docs-example';
     MatTabsModule,
     MatToolbarModule,
     MatTooltipModule,
+    MatTreeModule,
   ]
 })
 export class DemoMaterialModule {}