Add basic README

A simple README with a short summary of the project and a link
directing people to the online documentation.

README.markdown

@@ -0,0 +1,8 @@
+Native ZFS for Linux! ZFS is an advanced file system and volume manager
+which was originally developed for Solaris. It has been successfully 
+ported to FreeBSD and now there is a functional Linux ZFS kernel port
+too. The port currently includes a fully functional and stable SPA, DMU,
+and ZVOL with a ZFS Posix Layer (ZPL) on the way!
+
+Documentation for building, configuring, and using ZFS can be found at:
+<http://wiki.github.com/behlendorf/zfs/>