include example in sysconfig docstring

Author: ned-deily

Lib/sysconfig/__init__.py

@@ -657,6 +657,7 @@ def get_platform():
 
     - linux-x86_64
     - macosx-15.5-arm64
+    - macosx-26.0-universal2 (macOS on Apple Silicon or Intel)
     - android-24-arm64_v8a
 
     For other non-POSIX platforms, currently just returns :data:`sys.platform`."""