Fixes for #5468

Module should not change the TransactionBehavior. It should be done in the final application.
Also, revised the document.

docs/en/Getting-Started.md

@@ -117,7 +117,9 @@ The solution has a layered structure (based on the [Domain Driven Design](Domain
 
 {{ if DB == "Mongo" }}
 
-> The [startup template](Startup-templates/Index.md) **disabled** unit of work transaction in the `.MongoDB` project by default. If your MongoDB server supported transaction, you can enable the `transaction` of unit of work manually:
+#### MongoDB Transactions
+
+The [startup template](Startup-templates/Index.md) **disables** transactions in the `.MongoDB` project by default. If your MongoDB server supports transactions, you can enable the it in the *YourProjectMongoDbModule* class:
 
   ```csharp
   Configure<AbpUnitOfWorkDefaultOptions>(options =>

docs/en/MongoDB.md

@@ -275,11 +275,9 @@ public class BookService
 
 > Important: You must reference to the `Volo.Abp.MongoDB` package from the project you want to access to the MongoDB API. This breaks encapsulation, but this is what you want in that case.
 
-#### Transaction
+### Transactions
 
-Starting from version 4.0, MongoDB supports transactions. ABP added support for MongoDB transactions in version 3.2. If you upgrade the project to version 3.2. You need add [MongoDbSchemaMigrator](https://github.com/abpframework/abp/blob/dev/templates/app/aspnet-core/src/MyCompanyName.MyProjectName.MongoDB/MongoDb/MongoDbMyProjectNameDbSchemaMigrator.cs) to your `.MongoDB` project.
-
-The [startup template](Startup-templates/Index.md) **disabled** unit of work transaction in the `.MongoDB` project by default. If your MongoDB server supported transaction, you can enable the `transaction` of unit of work manually:
+MongoDB supports multi-document transactions starting from the version 4.0 and the ABP Framework supports it. However, the [startup template](Startup-templates/Index.md) **disables** transactions by default. If your MongoDB **server** supports transactions, you can enable the it in the *YourProjectMongoDbModule* class:
 
 ```csharp
 Configure<AbpUnitOfWorkDefaultOptions>(options =>

templates/module/aspnet-core/src/MyCompanyName.MyProjectName.MongoDB/MongoDB/MyProjectNameMongoDbModule.cs

@@ -1,7 +1,6 @@
 using Microsoft.Extensions.DependencyInjection;
 using Volo.Abp.Modularity;
 using Volo.Abp.MongoDB;
-using Volo.Abp.Uow;
 
 namespace MyCompanyName.MyProjectName.MongoDB
 {
@@ -19,11 +18,6 @@ namespace MyCompanyName.MyProjectName.MongoDB
                  * options.AddRepository<Question, MongoQuestionRepository>();
                  */
             });
-
-            Configure<AbpUnitOfWorkDefaultOptions>(options =>
-            {
-                options.TransactionBehavior = UnitOfWorkTransactionBehavior.Disabled;
-            });
         }
     }
 }