more info regarding installer

[gaurav-dalvi]

Following things to be added to documentation. Please dont add as help in script. Let us aim to add in some readme.

1: please explain why we need contiv install. This is the most confusing part according to other people.

2: for public cloud list of ports to be opened

3: minimum number of nodes (master and worker) requirements. Will installer work on 1 master node only ? will install work one worked node only ? do we always need 1 master and equal or more than 1 worker nodes.

4: for public cloud do we need eth0 and eth1 interface ? or will just eth0 work ? why do we need two interfaces for public cloud if we are just supporting vxlan mode in public cloud