Document global-projection templates (#3549)

Author: brendancol

README.md

@@ -274,7 +274,7 @@ Built-in Numba JIT and CUDA projection kernels bypass pyproj for per-pixel coord
 
 | Name | Description | Source | NumPy xr.DataArray | Dask xr.DataArray | CuPy GPU xr.DataArray | Dask GPU xr.DataArray |
 |:----------:|:------------|:------:|:----------------------:|:--------------------:|:-------------------:|:------:|
-| [from_template](xrspatial/templates.py) | Empty study-area grid for a named region (CONUS, NYC, ...), a world city (London, Tokyo, ... in its UTM zone) or country code; `preserve='area'/'shape'` picks an EPSG projection by property; `list_templates()` lists every accepted name | Custom | ✅ | 🔼 | 🔼 | 🔼 |
+| [from_template](xrspatial/templates.py) | Empty study-area grid for a named region (CONUS, NYC, ...), a world city (London, Tokyo, ... in its UTM zone), a country code, or a whole-world projection (web_mercator, wgs84/latlon, equal_earth); `preserve='area'/'shape'` picks an EPSG projection by property; `list_templates()` lists every accepted name | Custom | ✅ | 🔼 | 🔼 | 🔼 |
 
 -----------
 

docs/source/reference/templates.rst

@@ -9,7 +9,9 @@ a region name, a world-city name, or a country code into a NaN-filled
 :class:`xarray.DataArray` that follows the xarray-spatial array contract, so it
 feeds straight into the rest of the library. Cities (national capitals, major
 regional metros, and recognizable US secondary cities) come back as a metro
-bounding box in their UTM zone.
+bounding box in their UTM zone. Whole-world canvases are available in a few
+projections too: ``'web_mercator'`` (EPSG:3857), ``'wgs84'`` / ``'latlon'``
+(EPSG:4326), and ``'equal_earth'`` (EPSG:8857).
 
 Call :func:`~xrspatial.templates.list_templates` to discover every name
 ``from_template`` accepts (curated regions, world cities, and country codes).