Modify line numbers to highlight (dotnet#12811)

Author: mrmowji

aspnetcore/tutorials/first-mvc-app/adding-model.md

@@ -175,7 +175,7 @@ The scaffolding tool automatically created a DB context and registered it with t
 
 Examine the following `Startup.ConfigureServices` method. The highlighted line was added by the scaffolder:
 
-[!code-csharp[](~/tutorials/first-mvc-app/start-mvc/sample/MvcMovie22/Startup.cs?name=snippet_ConfigureServices&highlight=15-18)]
+[!code-csharp[](~/tutorials/first-mvc-app/start-mvc/sample/MvcMovie22/Startup.cs?name=snippet_ConfigureServices&highlight=14-15)]
 
 The `MvcMovieContext` coordinates EF Core functionality (Create, Read, Update, Delete, etc.) for the `Movie` model. The data context (`MvcMovieContext`) is derived from [Microsoft.EntityFrameworkCore.DbContext](/dotnet/api/microsoft.entityframeworkcore.dbcontext). The data context specifies which entities are included in the data model: