Add example of version specific pkg.install in the pillar

[arthurzenika]

As far as I understand it, the pkg:wanted pillar key is fed directly to pkg.installed: pkgs so one can use that to have version specific specs :

    wanted:
      - git
      - less
      - bc
      - curl
      - fail2ban

replaced by

    wanted:
      - git
      - less
      - bc
      - curl
      - fail2ban: 0.10.2-2.1