Update README file with URLs.

Add information about where dependencies can be found, and where the
official Git repository for this module is located.

README

@@ -18,3 +18,19 @@ GNU Lesser General Public License for more details.
 You should have received a copy of the GNU Lesser General Public
 License along with this module.
 If not, see <http://www.gnu.org/licenses/>.
+
+
+
+===== DEPENDENCIES =====
+
+This module depends on these other Puppet modules:
+
+- cfgfile
+  Can be found at https://gitlab.liu.se/NSC/puppetmodules/cfgfile.git.
+
+
+
+===== OFFICIAL SOURCE =====
+
+The official Git repository for this module is located at
+https://gitlab.liu.se/NSC/puppetmodules/xen.