clarify that islink only really works if python knows about symlinks (closes #13143)
Patch from Yayoi Ukai.
diff --git a/Doc/library/os.path.rst b/Doc/library/os.path.rst
index 3cc60cb..ed3aaf4 100644
--- a/Doc/library/os.path.rst
+++ b/Doc/library/os.path.rst
@@ -185,7 +185,7 @@
.. function:: islink(path)
Return ``True`` if *path* refers to a directory entry that is a symbolic link.
- Always ``False`` if symbolic links are not supported.
+ Always ``False`` if symbolic links are not supported by the python runtime.
.. function:: ismount(path)