Documentation error in edgelabel argument

Start with the gplot docstring in src/plot.jl and the Documentation site's Function prototype section linked in the issue. Check how edgelabel is described in both places, then update the documentation so it matches the demonstrated behavior; done means neither location claims that nothing is accepted.

In the documentation in gplot function, the edgelabel argument says it can be both a vector or nothing, however, it can only be a vector.

I found the Union{Vector, Nothing} in the following places:

• Documentation site, in the "Function prototype" section (at the end of the page)
• In the docstring of gplot

Example:

julia> gplot(g, edgelabel = nothing)
ERROR: MethodError: no method matching iterate(::Nothing)
Closest candidates are:
  iterate(::Union{LinRange, StepRangeLen}) at range.jl:664
  iterate(::Union{LinRange, StepRangeLen}, ::Int64) at range.jl:664
  iterate(::T) where T<:Union{Base.KeySet{var"#s79", var"#s78"} where {var"#s79", var"#s78"<:Dict}, Base.ValueIterator{var"#s77"} where var"#s77"<:Dict} at dict.jl:693
  ...
Stacktrace:
 [1] isempty(itr::Nothing)
   @ Base .\essentials.jl:767
 [2] gplot(g::MetaDiGraph{Int64, Float64}, locs_x_in::Vector{Float64}, locs_y_in::Vector{Float64}; nodelabel::Nothing, nodelabelc::RGB{FixedPointNumbers.N0f8}, nodelabelsize::Float64, NODELABELSIZE::Float64, nodelabeldist::Float64, nodelabelangleoffset::Float64, edgelabel::Nothing, edgelabelc::RGB{FixedPointNumbers.N0f8}, edgelabelsize::Float64, EDGELABELSIZE::Float64, edgestrokec::RGB{FixedPointNumbers.N0f8}, edgelinewidth::Float64, EDGELINEWIDTH::Float64, edgelabeldistx::Float64, edgelabeldisty::Float64, nodesize::Float64, NODESIZE::Float64, nodefillc::RGB{FixedPointNumbers.N0f8}, nodestrokec::Nothing, nodestrokelw::Float64, arrowlengthfrac::Float64, arrowangleoffset::Float64, linetype::String, outangle::Float64)
   @ GraphPlot C:\Users\89446\.julia\packages\GraphPlot\vrIy8\src\plot.jl:121
 [3] gplot(g::MetaDiGraph{Int64, Float64}; layout::typeof(spring_layout), keyargs::Base.Iterators.Pairs{Symbol, Nothing, Tuple{Symbol}, NamedTuple{(:edgelabel,), Tuple{Nothing}}})
   @ GraphPlot C:\Users\89446\.julia\packages\GraphPlot\vrIy8\src\plot.jl:229
 [4] top-level scope
   @ REPL[17]:1

However with gplot(g, edgelabel = []) works fine.