OSDOCS#14939: Adding GitLab and Ping Identity to the list of tested direct auth OIDC providers

Author: bergerhoffer

modules/external-auth-providers.adoc

@@ -8,8 +8,14 @@
 
 Direct authentication has been tested with the following OpenID Connect (OIDC) identity providers:
 
+* Active Directory Federation Services for Windows Server 
+* GitLab
+* Google
 * Keycloak
 * Microsoft Entra ID
+* Okta
+* Ping Identity
+* Red Hat Single Sign-On
 
 [NOTE]
 ====