bpo-43757: Document os.path.realpath(strict=True) in 3.10 whatsnew. (GH-26090) (#26099)

(cherry picked from commit d1560d2429dff8e7d397801786e966dd33bb1bd7)

Co-authored-by: Barney Gale <barney.gale@gmail.com>

Co-authored-by: Barney Gale <barney.gale@gmail.com>
diff --git a/Doc/whatsnew/3.10.rst b/Doc/whatsnew/3.10.rst
index 8fd64f8..9394ee7 100644
--- a/Doc/whatsnew/3.10.rst
+++ b/Doc/whatsnew/3.10.rst
@@ -1089,6 +1089,14 @@
 and :data:`~os.O_NOFOLLOW_ANY` for macOS.
 (Contributed by Dong-hee Na in :issue:`43106`.)
 
+os.path
+-------
+
+:func:`os.path.realpath` now accepts a *strict* keyword-only argument. When set
+to ``True``, :exc:`OSError` is raised if a path doesn't exist or a symlink loop
+is encountered.
+(Contributed by Barney Gale in :issue:`43757`.)
+
 pathlib
 -------