Update Tutorials

docs/en/Tutorials/Part-10.md

@@ -377,7 +377,7 @@ namespace Acme.BookStore.Books
 
             //Prepare a query to join books and authors
             var query = from book in queryable
-                join author in _authorRepository on book.AuthorId equals author.Id
+                join author in await _authorRepository.GetQueryableAsync() on book.AuthorId equals author.Id
                 where book.Id == id
                 select new { book, author };
 
@@ -400,7 +400,7 @@ namespace Acme.BookStore.Books
 
             //Prepare a query to join books and authors
             var query = from book in queryable
-                join author in _authorRepository on book.AuthorId equals author.Id
+                join author in await _authorRepository.GetQueryableAsync() on book.AuthorId equals author.Id
                 select new {book, author};
 
             //Paging