explanation for beginners

_documentation/ldap.md

@@ -23,8 +23,10 @@ If you see an error message like this:
 ```
 laminas/laminas-ldap requires ext-ldap * -> it is missing from your system. Install or enable PHP's ldap extension.
 ```
-you have to install the PHP LDAP extension, e.g. on Ubuntu with `apt-get install php-ldap` first.
-FPM and CLI PHP use different configs, so installing might not be enough: use `php -m` to verify that the module is really loaded.  
+you have to install the PHP LDAP extension first:
+- e.g. on Ubuntu with `apt-get install php-ldap`
+- or with the PHP version prefixed `apt-get install php8.1-ldap`
+- FPM and CLI PHP use different configs, use `php -m` to verify that the module is really loaded  
 
 ### Activate LDAP authentication