instance admin

Rewritten-docs.md

@@ -2187,9 +2187,39 @@ anymore.
 
 ## Instance administrator
 
-@todo: who is this?
+Administrator of instance can be only one per instance. In addition to previous
+roles instance admin should be able to modify instance details, manage licences
+and take care of groups which belong to instance.
 
-@todo: creating groups right in the instance
+### Instance management
+
+List of all instances in system can be found under "Instances" link in sidebar.
+On the mentioned page there is a table of instances with their respective
+admins. If you are admin of one of them you can visit its page by clicking on
+the instance name. On instance details page you can find some description of
+instance, current groups hierarchy and form for creating new group.
+
+If you want to change some of the instance settings follow "Edit instance" link
+on instance details page. This will take you to instance editation page with
+corresponding form. In there you can fill following information:
+
+- name of the instance which will be visible to every other user
+- brief description of instance and for whom it is intended
+- checkbox if instance is open or not which means public or private (hidden from
+  potentional users)
+
+If you are done with editation, save filled information by clicking on "Update
+instance" button.
+
+If we go back to the instance details page you can find here "Create new group"
+box which is able to add group to instance. This form is the same as the one for
+creating subgroup in already existing group so we can skip description of form
+fields. After successful creation of group it should appear in "Groups
+hierarchy" box at the top of the page.
+
+### Licenses
+
+@todo: licenses
 
 
 ## Superadministrator