Yup, nobody in all the announcements or any other articles mentioning this new "github" has mentioned the WIKI (which is part of Gitlab) is not included in the free part of Github ... this is kind of critical IMHO
Really, the wiki is one of the worst features. Markdown based docs are far better and actually part of the repository
The project I work on uses both: In-repo docs as the authoritative/reference on the software, and the wiki as a collaboration tool with a low barrier of entry to users adding things.
We have non-developers so they can handle markdown but not much beyond that ... having a website where they can type stuff (this is just like wikipedia) helps us get them onboarded .. then they also can help with the issues, etc.