doc-timestamp.js

const fs = require("fs");

fs.readFile("./package.json", "utf8", (err, data) => {
    if (err) {
        console.error(err);
        process.exit(1);
    } else {
        const version = JSON.parse(data).version;
        fs.readFile("./README.md", "utf8", (err, original) => {
            if (err) {
                console.error(err);
                process.exit(1);
            } else {
                const replaced = original.replace("<!--DOCUMENT STAMP-->", `* Update date: \`${new Date()}\`\n* Build version: \`${version}\``);
                fs.writeFile("./README.md", replaced, (err, data) => {
                    if (err) {
                        console.error(err);
                        process.exit(1);
                    }
                });
            }
        });
    }
});