Fix typos found by codespell (#343)

Author: DimitriPapadopoulos

doc/validation.rst

@@ -40,7 +40,7 @@ The full set of validation checks can be activated by::
 
 The complete validation suite contains `many checks <validation_checks>`_
 including some for style, capitalization, and grammar.
-It is unlikely that reporting *all* validation warnings is desireable for
+It is unlikely that reporting *all* validation warnings is desirable for
 most use-cases.
 Individual checks can be excluded by including them in the set with the
 special keyword ``"all"``::

numpydoc/tests/test_validate.py

@@ -58,7 +58,7 @@ def plot(self, kind, color="blue", **kwargs):
 
     def swap(self, arr, i, j, *args, **kwargs):
         """
-        Swap two indicies on an array.
+        Swap two indices on an array.
 
         The extended summary can be multiple paragraphs, but just one
         is enough to pass the validation.
@@ -417,9 +417,9 @@ def multiple_variables_on_one_line(self, matrix, a, b, i, j):
         matrix : list of list
             A double list that represents a matrix.
         a, b : int
-            The indicies of the first value.
+            The indices of the first value.
         i, j : int
-            The indicies of the second value.
+            The indices of the second value.
 
         See Also
         --------
@@ -921,7 +921,7 @@ def no_type(self):
 
     def no_description(self):
         """
-        Provides type but no descrption.
+        Provides type but no description.
 
         Returns
         -------