Cleanup POSTINSTALL

POSTINSTALL.md

@@ -1,4 +1,5 @@
-This app comes with a pre-setup admin account with those credentials:
+This app comes with a pre-setup admin account:
+
 username: `admin`
 
 password: `123123`
@@ -10,10 +11,6 @@ New users can be created in the registration form of the app. Public registratio
 </nosso>
 
 <sso>
-Otherwise it is integrated with the Cloudron user management.
-However **before** adding Cloudron users to projects in Taiga, they have to login into the app once.
-Otherwise the app assumes this is an external user and will send an invite.
-
-Public registration is disabled. If required, please install an instance of
-Taiga without Cloudron user integration.
+**Cloudron users must login to the app before being able to add them to projects in Taiga**.
+Otherwise, the app assumes they are external users and sends an invite.
 </sso>