added Extending-Existing-Entities-Core-Angular to menu

Author: ismcagdas

docs/en/Extending-Existing-Entities-Core-Angular.md

@@ -142,7 +142,7 @@ Since **UserAppService** use **auto mapping**, no need to manually map Address t
 ```html
 <div class="form-group">
      <label for="Address">{{"Address" | localize}}</label>
-     <input id="Address" #surnameInput="ngModel" type="text" name="Address" class="form-control" [(ngModel)]="user.address">
+     <input id="Address" #addressInput="ngModel" type="text" name="Address" class="form-control" [(ngModel)]="user.address">
 </div>
 ```
 

docs/en/nav-aspnet-core-angular.json

@@ -384,7 +384,7 @@
             },
             {
               "text": "Extending Existing Entities",
-              "path": "Extending-Existing-Entities.md"
+              "path": "Extending-Existing-Entities-Core-Angular.md"
             },
             {
               "text": "Converting Create & Edit Modals to Angular Pages",