Apply suggestions from code review

Co-authored-by: Deepak Cherian <dcherian@users.noreply.github.com>

Author: slevang

src/zarr/core/indexing.py

@@ -967,9 +967,10 @@ def __iter__(self) -> Iterator[ChunkProjection]:
             # handle advanced indexing arrays orthogonally
             if self.is_advanced:
                 # NumPy can handle a single array-indexed dimension directly,
-                # which keeps slice dimensions as slices and avoids an
+                # which preserves full slices and avoids an
                 # unnecessary advanced-indexing copy. Integer-indexed
                 # dimensions still need the ix_ path for downstream squeezing.
+                # Example: we skip `ix_` for array[:, :, [1, 2, 3]] 
                 n_array_dims = sum(isinstance(sel, np.ndarray) for sel in chunk_selection)
 
                 if n_array_dims > 1 or self.drop_axes: