[Feature] More detail around using napari layers in the context of atlas visualisation

**Describe the solution you'd like**
in the `brainrender-napari` tutorial where we explain adding references, we should add links to explanations of key napari skills needed: layer reordering, visibility and colourmap, and toggling grid mode

**Additional context**
See https://github.com/brainglobe/brainrender-napari/issues/249#issuecomment-4441903912