Docs: update user guide, add host netdevice settings, set hugepage size to 0

1. Update user guide, add host netdevice operations to make sure the testing CNF can work.
2. Reduce the hugepage size to 0, fix the issue that if the host does not have 2M hugepage setting will be failed
3. Add export OAM IP environment variable, avoid many times hand change.
4. 'helm push' not exist issue fixed with install helm plugin.

Signed-off-by: Zhang Rong(Jon) <rong.zhang@windriver.com>
Change-Id: If90f56005c93e9ac428fb06acf205b342a32363a