Add option to add a rule card

[siemdejong]

Is your feature request related to a problem? Please describe.
The rules have to be known by the player.

Describe the solution you'd like
Create a card with the rules. Optionally.

Describe alternatives you've considered
Let the user make their card externally.

[siemdejong]

The user could click on a button to show the default rules in markdown and edit it before generating cards.