avocado/linux/distro.py: remove misleading module docstring

The mentioned utility function, get_os_vendor() is actually an Autotest
specific thing and it has no place in avocadoland.
Signed-off-by: NCleber Rosa <crosa@redhat.com>

avocado/linux/distro.py

@@ -15,8 +15,6 @@
 """
 This module provides the client facilities to detect the Linux Distribution
 it's running under.
-
-This is a replacement for the get_os_vendor() function from the utils module.
 """
 
 import os