doc: fix outdated output msg in the assert example [av skip]

[gloine]

This is a minor fix:

macro assert(ex)
    return :($ex ? nothing : error("Assertion failed: ", $(string(ex))))
end

gives me

julia> @assert 1==0
ERROR: Assertion failed: 1 == 0

but the current documentation says

julia> @assert 1==0
ERROR: AssertionError: 1 == 0

which could be confusing for beginners like me. :)

[tkelman]

This would cause the doctest to fail, since the doctest does not include the above section that defines a new @assert macro. So it's instead calling the built-in @assert macro. Maybe we could modify the above macro definition to be more consistent and say throw(AssertionError($(string(ex)))) instead of error("Assertion failed: ", $(string(ex))) ?

[gloine]

I have tried to modify the example as you suggested and make the rest of the document be consistent with the modification. Hope it works...

[jakebolewski]

Thanks @gloine!