remove mention of num_vertices and num_edges in the documentation

Author: etiennedeg

src/layout.jl

@@ -195,9 +195,9 @@ Vector of Vector, Vector of node Vector for each shell.
 **Examples**
 ```
 julia> g = smallgraph(:karate)
-julia> nlist = Array{Vector{Int}}(2)
-julia> nlist[1] = [1:5]
-julia> nlist[2] = [6:num_vertiecs(g)]
+julia> nlist = Vector{Vector{Int}}()
+julia> push!(nlist, collect(1:5))
+julia> push!(nlist, collect(6:nv(g)))
 julia> locs_x, locs_y = shell_layout(g, nlist)
 ```
 """
@@ -242,7 +242,7 @@ the edge weight.  If None, then all edge weights are 1.
 **Examples**
 ```
 julia> g = smallgraph(:karate)
-julia> weight = rand(num_edges(g))
+julia> weight = rand(ne(g))
 julia> locs_x, locs_y = spectral_layout(g, weight)
 ```
 """