Submount subfs installation intructions.

To compile and install the module, the kernel with which you will use the
module should be running.  The makefile expects to find the kernel source
directory linked to /lib/modules/<kernel-version>/build, as it should
have been by the "make modules_install" command.  The cuurent version should
work with kernel versions starting with 2.6.0-test1.

Type "make" in this directory, and then, as root, type "make install".  The
module is named subfs.ko, and is installed in the
/lib/modules/<kernel-version>/kernel/fs/subfs directory.  "modprobe subfs"
should load the module.

For usage instructions, see the README file in the top level directory of the
submount package.
