docs: add domain model docs (#218)

website/data/docs-navigation.js

@@ -13,8 +13,24 @@ export default [
     content: ['terminology', 'domain-model', 'reference-deployment'],
   },
   {
-    category: 'configuration',
-    content: ['auth-methods', 'projects', 'users', 'groups', 'roles', 'grants'],
+    category: 'domain-model',
+    content: [
+      'actions',
+      'auth-methods',
+      'grants',
+      'groups',
+      'hosts',
+      'host-catalogs',
+      'host-sets',
+      'organization',
+      'principals',
+      'projects',
+      'resources',
+      'scopes',
+      'targets',
+      'roles',
+      'users',
+    ],
   },
   {
     category: 'command-line',