better dataset desc

examples/problems/900_annotation_mapping.ipynb

@@ -52,7 +52,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "Load the {func}`~moscot.datasets.drosophila` dataset. `adata_sc` is the scRNA-seq and `adata_sp` is the spatial dataset."
+    "The {func}`~moscot.datasets.drosophila` dataset is an embryo of Drosophila melanogaster dataset described in {cite}`Li-spatial:22` with minimal pre-processing. `adata_sc` is the scRNA-seq and `adata_sp` is the spatial dataset."
    ]
   },
   {