Fix jldoctest example in mapreduce(...)

[thchr]

Previously, the example produced an error, as no such method exists; just a typo I imagine.

Out of curiosity: isn't it the intention of ```jldoctest ...``` that documentation-examples such as this one would be automatically checked and caught by Documenter.jl's doctests?

[KristofferC]

Yes, they are indeed supposed to be checked and the log suggest they are, e.g. https://travis-ci.org/JuliaLang/julia/jobs/439252959#L3548. If they are actually not running then that is bad and need fixing.

[thchr]

I see, thanks.
This particular line is ~8 months old, so unless I'm missing something (I guess CI will show) it ought to have produced an error for a while.

[mortenpi]

I don't think this particular docstring is included in the manual. I can only find https://docs.julialang.org/en/v1.1-dev/base/collections/#Base.mapreduce-Tuple{Any,Any,Any}

If it is not spliced into the manual then it does not get tested (a behaviour which I am planning to change with JuliaDocs/Documenter.jl#774).

[thchr]

Thanks, that explains it: indeed, it seems that hardly any of the array functionality from base/reducedim.jl is included in doc/src/base/arrays.md (I assume that is where it would fit?). That is probably not intentional..?

[fredrikekre]

That is probably not intentional..?

No, do you feel like adding it?

[thchr]

Sure; I can make a PR for that some time next week, probably. (Or add it to this one, but I guess it's more meaningful to separate it out)

[fredrikekre]

Just add it to this one when you get time.