Better documentation for table/column versioning

[javier]

In QuestDB we version tables and columns. But when looking at the current docs for the root directory structure we don't mention it.

This should be more evident, as apparently some users find it confusing
https://www.reddit.com/r/questdb/comments/1e2j11x/comment/ld9o15u/?context=3

[nwoolmer]

I recently had questions about this and how the MVCC works, at a talk.

[javier]

I have an idea how this work, but not sure how conflict resolution works here. I believe we do optimistic and if there is a different meta version we reject the payload, and then we just version table and column folders, but not 100% sure about all the implications