Add just guide (ublue-os#243)

README.md

@@ -89,7 +89,7 @@ System updates are image-based and automatic. Applications are logically seperat
     - `Ctrl`-`Alt`-`u` - will launch an Ubuntu image inside a terminal via [Distrobox](https://github.com/89luca89/distrobox), your home directory will be transparently mounted
     - A [BlackBox terminal](https://www.omgubuntu.co.uk/2022/07/blackbox-gtk4-terminal-emulator-for-gnome) is used just for this configuration
     - Use this container for your typical CLI needs or to install software that is not available via Flatpak or Fedora
-    - Optional [ubuntu-toolbox image](https://github.com/ublue-os/bluefin/pkgs/container/ubuntu-toolbox) with Python, NPM, and other convenience development tools.  `just distrobox-bluefin` to get started
+    - Optional [ubuntu-toolbox image](https://github.com/ublue-os/bluefin/pkgs/container/ubuntu-toolbox) with Python, NPM, and other convenience development tools.  `just distrobox-bluefin` to get started. To configure `just` follow the [guide](https://ublue.it/guide/just/).
     - Optional [universal image](https://mcr.microsoft.com/en-us/product/devcontainers/universal/about) with Python, Node.js, JavaScript, TypeScript, C++, Java, C#, F#, .NET Core, PHP, Go, Ruby, and and Conda. `just distrobox-universal` to get started
     - Refer to the [Distrobox documentation](https://distrobox.privatedns.org/#distrobox) for more information on using and configuring custom images
     - GNOME Terminal