Small wording fixes for docs (#226)

Author: timholy

README.md

@@ -4,4 +4,4 @@
 [![codecov.io](http://codecov.io/github/JuliaArrays/StructArrays.jl/coverage.svg?branch=master)](http://codecov.io/github/JuliaArrays/StructArrays.jl?branch=master)
 [![](https://img.shields.io/badge/docs-dev-blue.svg)](https://JuliaArrays.github.io/StructArrays.jl/stable)
 
-This package defined an array type, `StructArray`, which acts like an array of `struct` elements but which internally is stored as a list of arrays, typically one per field of the `struct`. See the [documentation](https://JuliaArrays.github.io/StructArrays.jl/stable) for details.
+This package defines an array type, `StructArray`, which acts like an array of `struct` elements but which internally is stored as a list of arrays, typically one per field of the `struct`. See the [documentation](https://JuliaArrays.github.io/StructArrays.jl/stable) for details.

docs/src/index.md

@@ -50,12 +50,12 @@ julia> x = StructArray((a = adata, b = bdata))
 It's also possible to create a `StructArray` by choosing a particular dimension to interpret as the components of a struct:
 
 ```jldoctest intro
-julia> x = StructArray{Complex{Int}}(adata; dims=1)  # along dimension 1, odd indexes are `re` and even indexes are `im`
+julia> x = StructArray{Complex{Int}}(adata; dims=1)  # along dimension 1, the first item `re` and the second is `im`
 2-element StructArray(view(::Matrix{Int64}, 1, :), view(::Matrix{Int64}, 2, :)) with eltype Complex{Int64}:
  1 + 3im
  2 + 4im
 
-julia> x = StructArray{Complex{Int}}(adata; dims=2)  # along dimension 2, odd indexes are `re` and even indexes are `im`
+julia> x = StructArray{Complex{Int}}(adata; dims=2)  # along dimension 2, the first item `re` and the second is `im`
 2-element StructArray(view(::Matrix{Int64}, :, 1), view(::Matrix{Int64}, :, 2)) with eltype Complex{Int64}:
  1 + 2im
  3 + 4im