Arrays must share the same dtype in meshgrid() (#298)

* Modify `meshgrid()` so arrays must share the same dtype

* must -> should for dtype behaviour in `meshgrid()`

Author: honno

spec/API_specification/creation_functions.md

@@ -320,7 +320,7 @@ Returns coordinate matrices from coordinate vectors.
 
 -    **arrays**: _<array>_
 
-     -   an arbitrary number of one-dimensional arrays representing grid coordinates. Must have numeric data types.
+     -   an arbitrary number of one-dimensional arrays representing grid coordinates. Each array should have the same numeric data type.
 
 -    **indexing**: _str_
 
@@ -340,7 +340,7 @@ Returns coordinate matrices from coordinate vectors.
 
          Similarly, for the three-dimensional case with input one-dimensional arrays of length `M`, `N`, and `P`, if matrix indexing `ij`, then each returned array must have shape `(M, N, P)`, and, if Cartesian indexing `xy`, then each returned array must have shape `(N, M, P)`.
 
-         The returned arrays must have a numeric data type determined by {ref}`type-promotion`.
+         Each returned array should have the same data type as the input arrays.
 
 (function-ones)=
 ### ones(shape, *, dtype=None, device=None)