Feature Workbench on GNOME developer material

[sonnyp]

Workbench is great for newcomers and learning, we should feature it in material for GNOME developers.

This is an issue to track progress and requirements

• [x] Blueprint
• [ ] https://apps.gnome.org/ “Development Tools”
• [ ] https://developer.gnome.org/
• [ ] https://gtk-rs.org/
• [x] https://gjs.guide/
• [ ] https://pygobject.readthedocs.io/en/latest/
• [x] https://vala.dev/

[sonnyp]

Thanks to @andyholmes Workbench is now featured on https://gjs.guide/