bug#14727: minor bug in DF(1) manpage and techinfo page

[D. Hugh Redelmeier]

The man page for DF says:

    If an argument is the absolute file name of a disk device node
    containing a mounted file system, df shows the space available on
    that file system rather than on the file system containing the
    device node (which is always the root file system).

Device nodes are not always on the root file system.  In particular,
on my Fedora 18 system, mount shows:

  devtmpfs on /dev type devtmpfs 
(rw,nosuid,seclabel,size=3038532k,nr_inodes=759633,mode=755)

Just removing the parenthetical comment fixes this.

Interestingly, the techinfo page is slightly different but still wrong:

    If an argument FILE is a disk device file containing a mounted
    file system, `df' shows the space available on that file system
    rather than on the file system containing the device node (i.e.,
    the root file system).

Another point about these sentences:

Does the pathname have to be absolute?  Experiments seem to indicate
that it does.  So the man page is more correct than the techinfo page.