Update docs example in Functions/Arg destructuring

[cormullion]

The example in Argument destructuring didn't work when I typed it in, so I changed the name to gap().

[JeffBezanson]

I assume you got the error "range must be imported to be extended"? I guess this change is fine, but surely there are other cases where we use Base function names in the manual like this (including minmax just above) so I'm not sure it's really worth fixing.

[ViralBShah]

It doesn't work as is because:

julia> range((min,max)) = max-min
ERROR: error in method definition: function Base.range must be explicitly imported to be extended

[ViralBShah]

I guess this is the sort of thing that should become a jldoctest.

[JeffBezanson]

This has whitespace errors, as the CI failures clearly indicated. Build broken.

[ViralBShah]

Fixed in e58c6e6

[ViralBShah]

I had forgotten this whitespace check inside the old CI bots - since we have a separate CI job for whitespace nowadays. Will look inside these for the old PRs.

[Keno]

If something is more than a few weeks old, please always do a new CI run.