Update deployment guide doc

After trying to deploy with vms, find some errors and additional
requirements that need to be added into the deployment guide.

Also add some minor updates in function.sh.

Signed-off-by: xudan16 <xudan16@huawei.com>
Change-Id: I91f1d4efb28178c79d6a68f011da2b165633f345
Reviewed-on: https://gerrit.opnfv.org/gerrit/c/kuberef/+/73233
Tested-by: jenkins-ci <jenkins-opnfv-ci@opnfv.org>
Reviewed-by: Rihab Banday <rihab.banday@ericsson.com>
Reviewed-by: Kanagaraj Manickam <kanagaraj.manickam@huawei.com>
Reviewed-by: Michael Pedersen <michaelx.pedersen@intel.com>
Reviewed-by: Georg Kunz <georg.kunz@ericsson.com>