2.2 upgrade to 2.3

I have a 2.2-31 node i i would like to upgrade it to 3.1 however the requirements are that i upgrade it first to 2.3

How is this done ?

apt-get update
apt-get upgrade ?

:confused:

I see there are special upgrade instructions from 2.3 to 3.1 but i do not see any instructions for 2.2 to 2.3

Thanks