sync.WaitGroup docs say "Note that calls with positive delta must happen before the
call to Wait, or else Wait may wait for too small a group."

This is notoriously confusing. Given
https://golang.org/issue/8054?c=10 :

"The rule for WaitGroup is: all Add's that can transition the counter from 0 to
>0 must happen before Wait. Add's with negative values, or Add's with positive values
which start when counter >0 can be executed at any time."


If that really is the guarantee, could the documentation be changed to state that? As
is, people read that "calls" as "all calls" or "at least one
call", and those lead to very different behavior.