Minor fixes

Author: dcherian

cf_xarray/accessor.py

@@ -2023,7 +2023,7 @@ def add_canonical_attributes(
             Print added attributes to screen.
         source : optional
             Path of `cf-standard-name-table.xml` or file object containing XML data.
-            If ``None``, use the default version associated with ``cf-xarray``.
+            If ``None``, use the latest CF standard name table (requires ``pooch``).
 
         Returns
         -------

pyproject.toml

@@ -22,7 +22,7 @@ dependencies = [
 dynamic = ["version"]
 
 [project.optional-dependencies]
-all = ["matplotlib", "pint", "shapely", "regex", "rich"]
+all = ["matplotlib", "pint", "shapely", "regex", "rich", "pooch"]
 
 [project.urls]
 homepage = "https://cf-xarray.readthedocs.io"