Due to lack of requirements installation on Azure README, the error
can happen:
"The ipaddr filter requires python's netaddr be installed on the
ansible controller"
It is nice to add the installation for Azure users.
The ansible-playbook needs to ssh-login to Azure virtual machines with
ssh keypair, and users need to specify ssh_public_keys for their own
ssh public key. The change of ssh_public_keys is mandatory.
So this updates contrib/azurerm/README.md to explain that.
In addition, the path of all.yml was wrong. That also is updated with
this.
