Update best practice db operation documents for async queryable.

docs/en/Best-Practices/Entity-Framework-Core-Integration.md

@@ -144,7 +144,7 @@ public virtual async Task<IdentityUser> FindByNormalizedUserNameAsync(
     bool includeDetails = true,
     CancellationToken cancellationToken = default)
 {
-    return await DbSet
+    return await (await GetDbSetAsync())
         .IncludeDetails(includeDetails)
         .FirstOrDefaultAsync(
             u => u.NormalizedUserName == normalizedUserName,
@@ -175,14 +175,15 @@ public static IQueryable<IdentityUser> IncludeDetails(
 }
 ````
 
-* **Do** use the `IncludeDetails` extension method in the repository methods just like used in the example code above (see FindByNormalizedUserNameAsync).
+* **Do** use the `IncludeDetails` extension method in the repository methods just like used in the example code above (see `FindByNormalizedUserNameAsync`).
 
 - **Do** override `WithDetails` method of the repository for aggregates root which have **sub collections**. Example:
 
 ````C#
-public override IQueryable<IdentityUser> WithDetails()
+public override async Task<IQueryable<IdentityUser>> WithDetailsAsync()
 {
-    return GetQueryable().IncludeDetails(); // Uses the extension method defined above
+    // Uses the extension method defined above
+    return (await GetQueryableAsync()).IncludeDetails();
 }
 ````
 

docs/en/Best-Practices/MongoDB-Integration.md

@@ -128,7 +128,7 @@ public async Task<IdentityUser> FindByNormalizedUserNameAsync(
     bool includeDetails = true,
     CancellationToken cancellationToken = default)
 {
-    return await GetMongoQueryable()
+    return await (await GetMongoQueryableAsync())
         .FirstOrDefaultAsync(
             u => u.NormalizedUserName == normalizedUserName,
             GetCancellationToken(cancellationToken)
@@ -139,8 +139,8 @@ public async Task<IdentityUser> FindByNormalizedUserNameAsync(
 `GetCancellationToken` fallbacks to the `ICancellationTokenProvider.Token` to obtain the cancellation token if it is not provided by the caller code.
 
 * **Do** ignore the `includeDetails` parameters for the repository implementation since MongoDB loads the aggregate root as a whole (including sub collections) by default.
-* **Do** use the `GetMongoQueryable()` method to obtain an `IQueryable<TEntity>` to perform queries  wherever possible. Because;
-  *  `GetMongoQueryable()` method automatically uses the `ApplyDataFilters` method to filter the data based on the current data filters (like soft delete and multi-tenancy).
+* **Do** use the `GetMongoQueryableAsync()` method to obtain an `IQueryable<TEntity>` to perform queries  wherever possible. Because;
+  *  `GetMongoQueryableAsync()` method automatically uses the `ApplyDataFilters` method to filter the data based on the current data filters (like soft delete and multi-tenancy).
   * Using `IQueryable<TEntity>` makes the code as much as similar to the EF Core repository implementation and easy to write and read.
 * **Do** implement data filtering if it is not possible to use the `GetMongoQueryable()` method.
 

docs/en/Best-Practices/Repositories.md

@@ -42,24 +42,6 @@ Task<IdentityUser> FindByNormalizedUserNameAsync(
 );
 ````
 
-* **Do** create a **synchronous extension** method for each asynchronous repository method. Example:
-
-````C#
-public static class IdentityUserRepositoryExtensions
-{
-    public static IdentityUser FindByNormalizedUserName(
-        this IIdentityUserRepository repository,
-        [NotNull] string normalizedUserName)
-    {
-        return AsyncHelper.RunSync(
-            () => repository.FindByNormalizedUserNameAsync(normalizedUserName)
-        );
-    }
-}
-````
-
-This will allow synchronous code to use the repository methods easier.
-
 * **Do** add an optional `bool includeDetails = true` parameter (default value is `true`) for every repository method which returns a **single entity**. Example:
 
 ````C#