Widget documentation

[elkowar]

All provided widgets need complete documentation. This should be automatically generated from comments in the source code

Acceptance criteria

• A strict format for the comments that document built-in widgets is designed
  • Links to the GTK-documentation of these widgets is provided if applicable
  • Attributes are documented, including type / all possible values where applicable
  • a description of the widget is included
  • a instanceof referencing-system is implemented which allows widget docs to link to all super-classes, automatically including the super-classes docs in the widget docs.
• A script that generates markdown documentation from these comments is implemented
• All built-in widgets are fully documented using the created format

[elkowar]

Widget documentation as well as the docs created in #17 is now available at https://elkowar.github.io/eww/main/ 🥳