Update datashader.md (#2415)

typo on subheader

Author: eranws

doc/python/datashader.md

@@ -36,7 +36,7 @@ jupyter:
 
 [datashader](https://datashader.org/) creates rasterized representations of large datasets for easier visualization, with a pipeline approach consisting of several steps: projecting the data on a regular grid, creating a color representation of the grid, etc.
 
-### Passing datashader rasters as a mabox image layer
+### Passing datashader rasters as a mapbox image layer
 
 We visualize here the spatial distribution of taxi rides in New York City. A higher density
 is observed on major avenues. For more details about mapbox charts, see [the mapbox layers tutorial](/python/mapbox-layers). No mapbox token is needed here.