docs(material/datepicker): import used locales in example

Author: mmalerba

src/components-examples/material/datepicker/datepicker-locale/datepicker-locale-example.ts

@@ -5,6 +5,8 @@ import {
   MAT_MOMENT_DATE_ADAPTER_OPTIONS,
 } from '@angular/material-moment-adapter';
 import {DateAdapter, MAT_DATE_FORMATS, MAT_DATE_LOCALE} from '@angular/material/core';
+import 'moment/locale/ja';
+import 'moment/locale/fr';
 
 /** @title Datepicker with different locale */
 @Component({