added -f and a note about enabling VTx
added -f and a note about enabling VTx

This closes #19

Signed-off-by: Erik Weber <849f151457bb8eadd39216920a773cd2085b6b5f@apache.org>

pdion891/cloudstack-docs-install,pdion891/cloudstack-docs-install,unodba/cloudstack-docs-install,apache/cloudstack-docs-install,unodba/cloudstack-docs-install,unodba/cloudstack-docs-install,pdion891/cloudstack-docs-install,apache/cloudstack-docs-install,apache/cloudstack-docs-install