Notify developers when an update is available

[jan-molak]

Docusaurus has a nice feature that tells developers that an update is available when they start the development server.
Something similar could be useful to Serenity/JS so that they are notified when there's an update.

╭────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╮
│                                                                                                                    │
│                                           Update available 2.0.1 → 2.1.0                                           │
│                                                                                                                    │
│                 To upgrade Docusaurus packages with the latest version, run the following command:                 │
│    `npm i @docusaurus/core@latest @docusaurus/plugin-client-redirects@latest @docusaurus/preset-classic@latest     │
│                                      @docusaurus/module-type-aliases@latest`                                       │
│                                                                                                                    │
╰────────────────────────────────────────────────────────────────────────────────────────────────────────────────────