Consider this code: myArray |> Array.indexed |> Array.maxBy snd |> fst

The code returns the index of the first max value. However, the documentation does not state this fact. I had to look into the implementation (I looked into the implementation of Array).

I propose to add this fact to the according documentatation pages (e.g. https://fsharp.github.io/fsharp-core-docs/reference/fsharp-collections-arraymodule.html#maxBy).

I can provide a PR, but I want to check first, whether it would have a chance to be accepted - maybe there is no such guarantee of returning the first maximum.