Simpler first example

Hello,

I think it would help to have a simpler first example with a Vector and NamedTuple

Here is a proposal.

julia> using StructArrays

julia> adata = [1, 2]
2-element Vector{Int64}:
 1
 2

julia> bdata = [10.1, 20.1]
2-element Vector{Float64}:
 10.1
 20.1

julia> x = StructArray{NamedTuple{(:a, :b), Tuple{Int, Float64}}}((adata, bdata))
2-element StructArray(::Vector{Int64}, ::Vector{Float64}) with eltype @NamedTuple{a::Int64, b::Float64}:
 (a = 1, b = 10.1)
 (a = 2, b = 20.1)

julia> x.a
2-element Vector{Int64}:
 1
 2

julia> x.b
2-element Vector{Float64}:
 10.1
 20.1

julia> x[1]
(a = 1, b = 10.1)

Any opinion?

Review the documentation's introductory example and compare it with the proposed Vector and NamedTuple example in the issue. Update the first example if appropriate, then verify that the Julia code and displayed results render correctly.