2
There is no other way around and you will have to follow the regular upgrade path. If you want to be through, download WinMerge or other comparing software, compare your RC2 with 2.0.6 to make sure if you have got all the right files, then upgrade.
Back up your whole site first before upgrade.
Next time, don't use RC (Release Candidate) version for your production site. It will save you tons of headache.