Misleading doc in FSharp.Core async

[thyecust]

fsharp/src/FSharp.Core/async.fsi

Line 810 in 723b1dc

/// Prints "C", then "A" quickly, and then "B" 1 second later

Similar to L116, the behaviour should be A and C quickly in any order, and then B after 1 second, right?

[thyecust]

Correct pr: #15574