docs: update keycloak.md (argoproj#17684)

* Update keycloak.md

The documentation is excellent, but after following it, i'v experienced an issue 401, and the UI loop to login, to fix it i restarted the argocd-server pod then it' worked well.

Signed-off-by: abdaziz <abdazizg@gmail.com>

* Update keycloak.md

update the requested changes from @wanghong230

Signed-off-by: abdaziz <abdazizg@gmail.com>

* Update keycloak.md

Signed-off-by: abdaziz <abdazizg@gmail.com>

* Update keycloak.md

good format.

Signed-off-by: abdaziz <abdazizg@gmail.com>

---------

Signed-off-by: abdaziz <abdazizg@gmail.com>

docs/operator-manual/user-management/keycloak.md

@@ -125,3 +125,9 @@ In this example we give the role _role:admin_ to all users in the group _ArgoCDA
 You can now login using our new Keycloak OIDC authentication:
 
 ![Keycloak ArgoCD login](../../assets/keycloak-login.png "Keycloak ArgoCD login")
+
+## Troubleshoot
+If ArgoCD auth returns 401 or when the login attempt leads to the loop, then restart the argocd-server pod.
+```
+kubectl rollout restart deployment argocd-server -n argocd
+```