minor typo in custom_raster_dataset.ipynb (#1987)

docs/tutorials/custom_raster_dataset.ipynb

@@ -345,7 +345,7 @@
     "\n",
     "### `rgb_bands`\n",
     "\n",
-    "If your data is a multispectral iamge, you can define which bands correspond to the red, green, and blue channels. In the case of Sentinel-2, this corresponds to B04, B03, and B02, in that order.\n",
+    "If your data is a multispectral image, you can define which bands correspond to the red, green, and blue channels. In the case of Sentinel-2, this corresponds to B04, B03, and B02, in that order.\n",
     "\n",
     "Putting this all together into a single class, we get:"
    ]