Add in hardocs guide to change environment variable in config when deploying in gitlab

In the base key, change the value to the repository name in gitlab. Otherwise it doesn't work.

module.exports = {
    title: "Name your project",
    //description : "use for meta descriptitrueon",
    base: "/" + process.env.REPOSITORY + "/",
    config: (md) => {
        md.options.linkify = sidebarArray;
    },
    themeConfig: {
        sidebar: sidebarArray
    }
};