Update install.sgml with the name of the example OS

We want the name of the example OS to be nicer for packagers, so update
the install documentation accordingly.

Also, put in a notice about using the latest release OS version, so if
we forget to update this doc, we are not completely wrong.

Reviewed-by: schreiberal

doc/install.sgml

@@ -645,13 +645,15 @@ mkdir /srv/ganeti/ /srv/ganeti/os /srv/ganeti/export
         provided on the project web site.  Download it from <ulink
         url="http://code.google.com/p/ganeti/"></ulink> and follow the
         instructions in the <filename>README</filename> file.  Here is
-        the installation procedure:
+        the installation procedure (replace <constant>0.2</constant>
+        with the latest version that is compatible with your ganeti
+        version):
       </para>
 
       <screen>
 cd /srv/ganeti/os
-tar xvf instance-debian-etch-0.2.tar
-mv instance-debian-etch-0.2 debian-etch
+tar xvf ganeti-instance-debian-etch-0.2.tar
+mv ganeti-instance-debian-etch-0.2 debian-etch
       </screen>
 
       <para>