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

diff --git a/Doc/library/pathlib.rst b/Doc/library/pathlib.rst
index 7a4a20d..41aebc4 100644
--- a/Doc/library/pathlib.rst
+++ b/Doc/library/pathlib.rst
@@ -976,7 +976,7 @@
    is raised.
 
    .. versionadded:: 3.6
-      The *strict* argument.
+      The *strict* argument (pre-3.6 behavior is strict).
 
 .. method:: Path.rglob(pattern)