add rules

docs/index.md

@@ -7,6 +7,7 @@ Aktuell findet Ihr hier:
 * [Maps Tutorial](maps.md)
 * [HowTo Play](play.md)
 * [Design/Styleguide](https://style.rc3.world)
+* [Spielregeln](rules.md)
 
 This pages should give you an overview over rC3 2021, connected services, as well
 as how to contribute to rC3.
@@ -16,6 +17,7 @@ For now, you can find the following here:
 * [Maps Tutorial](maps.en.md)
 * [HowTo Play](play.en.md)
 * [Design/Styleguide](https://style.rc3.world)
+* [Rules](rules.en.md)
 
 
 <!--

mkdocs.yml

@@ -31,4 +31,5 @@ nav:
 #  - Workadventure: 'workadventure.en.md'
   - Play: 'play.md'
   - Styleguide: 'https://style.rc3.world'
+  - Rules: 'rules.md'
 #  - Sponsoring: 'sponsoring.md'