Update asyncmap docs to clarify order of outputs

[haakon-e]

small addition to asyncmap docstring to clarify that order of output is same as input:

The output is guaranteed to be the same order as the elements of the collection(s) c.

I added it to clarify the behavior, especially for new users, and, afaik because it is not consistent across programming languages.

Happy to iterate if there should be updates to doc pages too.

[Seelengrab]

Should this actually be guaranteed, or is this a case of "that's what it happens to do right now"?

[haakon-e]

Should this actually be guaranteed, or is this a case of "that's what it happens to do right now"?

I will have to defer a definitive answer to that question for someone else. I'm basing my PR on the answer to a question I had about this in the julia slack. In any case, clarification either way for what I should expect (or not expect) would be useful to have in the docs.

[ericphanson]

It should be semantically guaranteed since it is supposed to be like map (and this order is a big reason this function is useful)

[LilithHafner]

Thanks!