themeless page should respect "order" configuration

[johnnychen94]

In JuliaImages/juliaimages.github.io#159, even though the "order" is specified:

{
    "order":[
        "introduction",
        "axes",
        "metadata",
        "features",
        "segmentation",
        "transformations"
    ]
}

it uses some unknown order instead of the customized order.