Cubemap Layout

**Your Godot version:**
Godot 4.3

**Issue description:**
The documentation specifies the order of the tiles for a Cubemap texture (+X, -X, +Y, -Y, +Z, -Z), but says nothing about how these tiles should be rotated. As this is difficult to describe, I would've expected the cubemap templates to at least indicate this, but they don't.

Ideally, the cubemap example images should specify which edges align. e.g, On the +X tile, it should specify which sides of it connect to the +Y, -Y, +Z, and -Z tiles.

I'd be happy to submit a PR if I actually knew the alignment myself. If someone could point out an article or even provide a working sample image, I could infer this and submit a PR.

**URL to the documentation page (if already existing):**
https://docs.godotengine.org/en/stable/classes/class_cubemap.html
https://docs.godotengine.org/en/stable/tutorials/assets_pipeline/importing_images.html