gem install with knife 12.4

[tiago-cruz-movile]

• knife version

tiagocruz@stark:~$ knife -v
Chef: 12.4.1

• NOK

tiagocruz@stark:~$ sudo gem install knife-softlayer
[sudo] password for tiagocruz: 
Fetching: builder-3.2.2.gem (100%)
Fetching: excon-0.45.4.gem (100%)
Fetching: formatador-0.2.5.gem (100%)
Fetching: fog-core-1.35.0.gem (100%)
Fetching: fog-json-1.0.2.gem (100%)
Fetching: fog-softlayer-0.3.30.gem (100%)
Fetching: ffi-1.9.10.gem (100%)
Building native extensions.  This could take a while...
Fetching: gssapi-1.2.0.gem (100%)
Fetching: httpclient-2.7.0.1.gem (100%)
Fetching: rubyntlm-0.4.0.gem (100%)
Fetching: uuidtools-2.1.5.gem (100%)
Fetching: little-plugger-1.1.4.gem (100%)
Fetching: logging-2.0.0.gem (100%)
Fetching: nori-2.6.0.gem (100%)
Fetching: gyoku-1.3.1.gem (100%)
Fetching: winrm-1.4.0.gem (100%)
Fetching: winrm-s-0.3.2.gem (100%)
Fetching: knife-windows-1.1.2.gem (100%)
Fetching: net-ssh-3.0.2.gem (100%)
ERROR:  Error installing knife-softlayer:
    net-ssh requires Ruby version >= 2.0.

• OK:

tiagocruz@stark:~$ chef gem install knife-softlayer
Fetching: fog-softlayer-0.3.30.gem (100%)
WARNING:  You don't have /home/tiagocruz/.chefdk/gem/ruby/2.1.0/bin in your PATH,
      gem executables will not run.
Successfully installed fog-softlayer-0.3.30
Fetching: knife-softlayer-0.4.0.gem (100%)
Successfully installed knife-softlayer-0.4.0
2 gems installed

Please update the README :)