DOC: Shorten release note about FPE warnings in casts

Co-authored-by: Matti Picus <matti.picus@gmail.com>

doc/release/upcoming_changes/21437.improvement.rst

@@ -8,26 +8,13 @@ For examples, casts like::
     np.array([2e300]).astype(np.float32)  # overflow for float32
     np.array([np.inf]).astype(np.int64)
 
-Should now generally give floating point warnings.  These warnings
-should warn that floating point overflow occurred.
-For errors when converting floating point values to integers users
-should expect invalid value warnings.
+Should now generally give floating point overflow warnings.
+Errors when converting floating point values to integers may emit 
+invalid value warnings.
 
 Users can modify the behavior of these warnings using `np.errstate`.
 
 Note that for float to int casts, the exact warnings that are given may
-be platform dependend.  For example::
-
-    arr = np.full(100, value=1000, dtype=np.float64)
-    arr.astype(np.int8)
-
-May give a result equivalent to (the intermediat means no warning is given)::
-
-    arr.astype(np.int64).astype(np.int8)
-
-May may return an undefined result, with a warning set::
-
-    RuntimeWarning: invalid value encountered in cast
-
-The precise behavior if subject to the C99 standard and its implementation
+be platform dependent.
+The precise behavior is subject to the C99 standard and its implementation
 in both software and hardware.