Out dated/Incorrect information in Documentation: Viewport as Texture edition.

**Your Godot version: v4.3.stable.steam**

**Issue description: Out dated/Incorrect information in Documentation**

**URL to the documentation page: https://docs.godotengine.org/en/stable/tutorials/shaders/using_viewport_as_texture.html**

Unfortunately I was unable to find a solution on my side that works within what the Doc says.

The problem comes at the point where you are to add a ViewportTexture to the object. That is simply impossible, as an error pops up informing you "Can't create a ViewportTexture on resources saved as a file. Resource needs to belong to a scene.". I tried a clean slate project, a different scene, whatever else I could think of.

I'm either extremely stupid, or this is simply incorrect information on the Doc.