Docs for missing values

I got confused by the following query

metrics = @from i in data0 begin
    @where i.happy != "NA" && i.energetic != "NA" && !ismissing(i.ActualStartTime)
    @select {i.ParticipantID, happy=round(Int, i.happy), energy=round(Int, i.energetic), i.sex, time=i.ActualStartTime}
    @collect DataFrame
end

and I expected the resulting dataframe to not contain any records for which time is missing, but no filtering took place. I had it explained for me on Zulip, that missing are translated to DataValues. The docs https://www.queryverse.org/Query.jl/stable/gettingstarted/#Missing-values-1
are not super clear on this and I did not expect this behavior even after having read that part of the docs again. In particular, the docs do not really mention what to use instead of ismissing or how I can opt out of the automatic translation if it all possible.

Start with the “Missing values” section of the Query.jl getting-started documentation linked in the issue, and compare it with the reported query using ismissing. Update the documentation so it clearly explains the DataValues translation, what users should use instead of ismissing, and whether automatic translation can be disabled.