Draft: feat(discourse): add discourse config and plugin installation

Closes #14 (closed)

defaults/main.yml

@@ -56,3 +56,14 @@ ynh_apps: null
   #   args:
   #     domain: domain.tld
   #     path: /ttrss
+
+ynh_discourse_settings:
+  title: "Let's go!"
+  site_description: "Hello"
+  contact_email: "arthur_ynh@{{ ynh_main_domain }}"
+  invite_only: "true"
+  backup_frequency: "1"
+  maximum_backups: "60"
+
+ynh_discourse_plugins:
+  cakeday: "https://github.com/discourse/discourse-cakeday"