Directions for upgrading from 2.9 to 3.0 missing?

Hi there. We are currently running 2.9 Supporter and wish to upgrade to Pro Sites. I remember when the new version came out you had detailed instructions on how to upgrade to the new 3.0 version. I can't seem to find those online anymore so I wanted to see if you could provide a link to those instructions for us.

Thanks so much for your time