Doc: Be explicit that Pathlib resolve was strict before 3.6. (GH-11316)

(cherry picked from commit 1d4b160)

Co-authored-by: Julien Palard <[email protected]>

Author: miss-islington

Doc/library/pathlib.rst

@@ -966,7 +966,7 @@ call fails (for example because the path doesn't exist):
    is raised.
 
    .. versionadded:: 3.6
-      The *strict* argument.
+      The *strict* argument (pre-3.6 behavior is strict).
 
 .. method:: Path.rglob(pattern)