update docs

docs/30_Requirements.md

@@ -2,3 +2,4 @@
 
 * PHP 8 (up to 8.3)
 * PHP web application with mod_shibboleth
+* Shibboleth must be configured to allow logins from other organizations

docs/40_Installation.md

 ## Installation
 
-* In the webroot create a subfolder "login_aai".
+* In the webroot create a subfolder "login_aai". 
+* Extract the files there.
+* Do NOT protect this folder with Shibboleth that it can be accessed anonymous
+* Copy config.php.dist to config.php and make your changes. See chapter Configuration.
 * Set a Link for Login to `/login_aai/` where needed
-* Copy config.php.dist to config.php and make your changes.
+
+The web ui offers just a frontend for your visitors to link multiple organisations.
+
+That the login at other IDP work you need to
+
+* create a Service provider on your AAI Federation
+* configure Shibboleth and whitelist the wanted IDPs
+* For access from other federations (countries):
+  * You and your partner need to enablle EDUGAIN.
+  * The parter IDP must enable the domain of your website
+
+Links:
+
+* <https://en.wikipedia.org/wiki/Shibboleth_(software)>
+* <https://met.refeds.org/>