setup.py: add note about llfuse 0.42

setup.py

@@ -24,6 +24,7 @@ install_requires = ['msgpack-python>=0.4.6', ]
 extras_require = {
     # llfuse 0.40 (tested, proven, ok), needs FUSE version >= 2.8.0
     # llfuse 0.41 (tested shortly, looks ok), needs FUSE version >= 2.8.0
+    # llfuse 0.42 (tested shortly, looks ok), needs FUSE version >= 2.8.0
     # llfuse 1.0 will break API
     'fuse': ['llfuse<1.0', ],
 }