Update docs

docs/en/MongoDB.md

@@ -254,7 +254,7 @@ public async override Task DeleteAsync(
 
 ### Access to the MongoDB API
 
-In most cases, you want to hide MongoDB APIs behind a repository (this is the main purpose of the repository). However, if you want to access the MongoDB API over the repository, you can use `GetDatabaseAsync()` or `GetCollectionAsync()` extension methods. Example:
+In most cases, you want to hide MongoDB APIs behind a repository (this is the main purpose of the repository). However, if you want to access the MongoDB API over the repository, you can use `GetDatabaseAsync()`, `GetCollectionAsync()` or `GetAggregateAsync()` extension methods. Example:
 
 ```csharp
 public class BookService
@@ -270,6 +270,7 @@ public class BookService
     {
         IMongoDatabase database = await _bookRepository.GetDatabaseAsync();
         IMongoCollection<Book> books = await _bookRepository.GetCollectionAsync();
+        IAggregateFluent<Book> bookAggregate = await _bookRepository.GetAggregateAsync();
     }
 }
 ```

docs/zh-Hans/MongoDB.md

@@ -211,7 +211,7 @@ public async override Task DeleteAsync(
 
 #### 访问MongoDB API
 
-大多数情况下,你想要将MongoDB API隐藏在仓储后面(这是仓储的主要目的).如果你想在仓储之上访问MongoDB API,你可以使用`GetDatabase()`或`GetCollection()`方法.例如:
+大多数情况下,你想要将MongoDB API隐藏在仓储后面(这是仓储的主要目的).如果你想在仓储之上访问MongoDB API,你可以使用`GetDatabaseAsync()`, `GetAggregateAsync()` 或`GetCollectionAsync()`方法.例如:
 
 ```csharp
 public class BookService
@@ -223,10 +223,11 @@ public class BookService
         _bookRepository = bookRepository;
     }
 
-    public void Foo()
+    public async Task FooAsync()
     {
-        IMongoDatabase database = _bookRepository.GetDatabase();
-        IMongoCollection<Book> books = _bookRepository.GetCollection();
+        IMongoDatabase database = await _bookRepository.GetDatabaseAsync();
+        IMongoCollection<Book> books = await _bookRepository.GetCollectionAsync();
+        IAggregateFluent<Book> bookAggregate = await _bookRepository.GetAggregateAsync();
     }
 }
 ```