Change navbar link to Movies controller

[manishm004]

Text below the code snippet mentions the navbar link as Movies controller
Hence the change is necessary for the code to be in sync with the explanation just below it.

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File	Preview link
aspnetcore/tutorials/first-mvc-app/start-mvc/sample/MvcMovie90/Views/Shared/_Layout.cshtml	Learn preview

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[wadepickett]

@manishm004, Thanks very much for offering to help here.

I think there is some confustion about the state the _Layout.cshtml has to represent at a particular point in the tutorial series. Over the course of steps it needs to represent one state and then later we have source that represents a later state after steps in the tutorial have been completed. The file you want to change in this PR represents an earlier state, not the completed state and needs to stay as is. (The PR should not change the file and the PR should be closed.)

The completed app example lives here in the sample/9.0-completed folder:
https://github.com/dotnet/AspNetCore.Docs/tree/main/aspnetcore/tutorials/first-mvc-app/start-mvc/sample/9.0-completed

Here is a table to lay that all out where we can see it. This tutorial series contains a lot of progressive states as each new subject is taught.

Why the navbar brand link is HelloWorld in Part 3 (and shouldn't be changed to Movies):

The Get started with ASP.NET Core MVC series (aspnetcore/tutorials/first-mvc-app/) is deliberately built as a progression: you start with a temporary "example A" state and are later shown how to change it to "example B." The navbar brand link's asp-controller value is one of those things that intentionally starts as one value and changes later. Here's the full arc:

#	Tutorial	Doc file	What's being taught	Navbar brand asp-controller state (and why)
1	Get started	start-mvc.md	Create the MVC project from the template; run the default app.	Default template value (Home) — no custom controller exists yet.
2	Add a controller	adding-controller.md	Create HelloWorldController; understand controllers/actions and routing (/HelloWorld).	The only controller you've built is HelloWorld. This establishes "example A."
3	Add a view (this PR)	adding-view.md	Move from returning strings to Razor views; edit _Layout.cshtml; introduce ViewData to pass data from controller → view.	HelloWorld — correct and intentional. The Movies controller doesn't exist yet; the tutorial explicitly notes the "Movie App" link "isn't functional" at this point. Pointing at HelloWorld matches the app you actually have.
4	Add a model	adding-model.md	Add the Movie model + EF Core; scaffold MoviesController and Views/Movies/*; move to strongly-typed models bound to database data.	This is where it legitimately changes to Movies. Now that MoviesController exists, the "Movie App" link should route to /Movies — the "Test the app" step says "select the Movie App link" and shows the movie list. This is the "example A → example B" transition.
5	Work with SQL	working-with-sql.md	Seed/query data; work directly with the database.	Movies (end state established in Part 4 continues).
6	Controller methods and views	controller-methods-views.md	Refine the scaffolded Movies controller actions and views.	Movies.
7	Add search	search.md	Add query-string search/filtering to the movie list.	Movies.
8	Add a new field	new-field.md	Add a model property and apply a migration.	Movies.
9	Add validation	validation.md	Add DataAnnotations validation.	Movies.
10	Details & Delete	details.md	Examine the generated Details/Delete methods.	Movies — matches the *-completed samples (the final state).

The key point for this PR

• The brand link's value is a navigation target, not a displayed value. The label "Movie App" is a hard-coded string the whole time — it never becomes data-driven. Only the destination controller changes: HelloWorld (Part 3) → Movies (Part 4).
• So in Part 3, asp-controller="HelloWorld" is the correct, intentional temporary state. Changing it to Movies (as this PR suggests) skips ahead to a controller that doesn't exist yet and breaks the deliberate "start here, change it later" teaching device.

Two source-code collections (as expected in this series)

• Per-step "state" samples (start-mvc/sample/MvcMovie10, MvcMovie90, MvcMovie80, …): capture each intermediate state. For Part 3, these should use HelloWorld.
• Completed apps (start-mvc/sample/*-completed): the final state, which correctly uses Movies.