TODO: Check if ths documentation is correct

Signed-off-by: Julian-Samuel Gebühr <julian-samuel@gebuehr.net>

docs/configuring-playbook-matrix-ldap-registration-proxy.md

@@ -14,3 +14,17 @@ Add the following configuration to your `inventory/host_vars/matrix.DOMAIN/vars.
 ```yaml
 matrix_ldap_registration_proxy_enabled: true
 ```
+
+That is enough if you use the synapse external password provider via LDAP.
+If you want to use your own credentials add the following to your  `inventory/host_vars/matrix.DOMAIN/vars.yml`:
+
+
+
+# LDAP credentials
+```yaml
+matrix_ldap_registration_proxy_ldap_uri: <URI>
+matrix_ldap_registration_proxy_ldap_base_dn: <DN>
+matrix_ldap_registration_proxy_ldap_user: <USER>
+matrix_ldap_registration_proxy_ldap_password: <password>
+```
+TODO: is the block above correct? Else indicate that it can only be used with the LDAP password provider for Synapse