Remove ambiguity in docs for ndarray.byteswap()

This fixes numpy#27628. Thanks to @Shezeeblanka for pointing out the
potential ambiguity in the documentation of numpy.ndarray.byteswap().
This commit explicitly mentions the datatype of the array A so that
running the code snippet would yield reproducible results.

Author: SoutrikBandyopadhyay

numpy/_core/_add_newdocs.py

@@ -3310,7 +3310,7 @@
     ``A.view(A.dtype.newbyteorder()).byteswap()`` produces an array with
     the same values but different representation in memory
 
-    >>> A = np.array([1, 2, 3])
+    >>> A = np.array([1, 2, 3],dtype=np.int64)
     >>> A.view(np.uint8)
     array([1, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0,
            0, 0], dtype=uint8)