Add some missing notes to array_api

Original NumPy Commit: b5ac835f2e1d1188d2f0ab961cadbb74e1e488d0

Author: asmeurer

array_api_strict/_sorting_functions.py

@@ -5,6 +5,7 @@
 import numpy as np
 
 
+# Note: the descending keyword argument is new in this function
 def argsort(
     x: Array, /, *, axis: int = -1, descending: bool = False, stable: bool = True
 ) -> Array:
@@ -31,7 +32,7 @@ def argsort(
         res = max_i - res
     return Array._new(res)
 
-
+# Note: the descending keyword argument is new in this function
 def sort(
     x: Array, /, *, axis: int = -1, descending: bool = False, stable: bool = True
 ) -> Array: