Fix typos on docstrings (#281)

Fix typo on description of data_names parameters on BaseGridder.grid
method. Fix typo on description of BaseGridder.project_coordinates
method.

verde/base/base_classes.py

@@ -380,7 +380,7 @@ def grid(
             order: northing dimension, easting dimension.
             **NOTE: This is an exception to the "easting" then
             "northing" pattern but is required for compatibility with xarray.**
-        data_names : list of None
+        data_names : list or None
             The name(s) of the data variables in the output grid. Defaults to
             ``['scalars']`` for scalar data,
             ``['east_component', 'north_component']`` for 2D vector data, and
@@ -659,7 +659,7 @@ def _get_extra_coords_names(self, coordinates):
 
 def project_coordinates(coordinates, projection, **kwargs):
     """
-    Apply projection to given coordiantes
+    Apply projection to given coordinates
 
     Allows to apply projections to any number of coordinates, assuming
     that the first ones are ``longitude`` and ``latitude``.