Doc: Further steps if firewalld is not installed

[aditya-konarde]

Here: https://github.com/praveenkumar/osp4/blob/master/libvirt/minishift_libvirt.sh#L34

For a naive user, might be better to tell them to install/enable firewalld, or enable it by ourselves like we are enabling libvirtd. Wdyt?

[aditya-konarde]

/label enhancement :)

[gbraad]

ideally we check the host platform:

• if RHEL/CentOS, use yum, else if Fedora, use dnf.
• check for components needed
  • if not installed, perform install
  • enable and start required components
• verify if components are working
• continue as-is

where components is libvirtd, firewalld, etc.

[praveenkumar]

Right now yum command is present for RHEL/CentOS and Fedora so we just need to perform the installation if not present and activate it.