Clarify mixed kind promotion is unspecified for divide notes

Author: honno

spec/API_specification/array_object.md

@@ -1250,7 +1250,7 @@ Element-wise results must equal the results returned by the equivalent element-w
 Evaluates `self_i / other_i` for each element of an array instance with the respective element of the array `other`.
 
 ```{note}
-If one or both of `self` and `other` have integer data types, the result is unspecified and thus implementation-dependent.
+If one or both of `self` and `other` have integer data types, the result is unspecified and thus implementation-dependent (type promotion between data type “kinds” (integer versus floating-point) is unspecified).
 ```
 
 #### Special Cases

spec/API_specification/elementwise_functions.md

@@ -529,7 +529,7 @@ For floating-point operands,
 Calculates the division for each element `x1_i` of the input array `x1` with the respective element `x2_i` of the input array `x2`.
 
 ```{note}
-If one or both of the input arrays have integer data types, the result is unspecified and thus implementation-dependent.
+If one or both of the input arrays have integer data types, the result is unspecified and thus implementation-dependent (type promotion between data type “kinds” (integer versus floating-point) is unspecified).
 ```
 
 #### Special Cases