Add a note to the platform.machine() documentation section

Author: Aniketsy

Doc/library/platform.rst

@@ -56,6 +56,13 @@ Cross platform
    Returns the machine type, e.g. ``'AMD64'``. An empty string is returned if the
    value cannot be determined.
 
+   .. note::
+
+      The output of :func:`platform.machine` is system-dependent and may differ in casing
+      and naming conventions across platforms. For example, on Apple Silicon macOS it may
+      return ``'arm64'`` (lowercase), while on Windows-on-ARM it may return ``'ARM64'`` (uppercase).
+      If you need consistent results, normalize the output in your code.
+
 
 .. function:: node()