Document workaround for bnc#792839

Most likely there won't be any fix, since the issue does only happen
with a XEN SLES10 guest on a XEN SLES10 host.
Merge pull request #68 from thardeck/document_bnc_792839

Document workaround for bnc#792839
Merge branch 'master' of github.com:susestudio/studio-help into upstream

* 'master' of github.com:susestudio/studio-help:
  Document workaround for bnc#792839