Including info on OpenID Additional Parameters (#5600) (#5643)

* Including info on OpenID Additional Parameters



* Update _security/authentication-backends/openid-connect.md




* Update _security/authentication-backends/openid-connect.md




* PR feedback changes



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(cherry picked from commit 4af8a0d)

Signed-off-by: Sam <samuel.costa@eliatra.com>
Signed-off-by: Sam <128482925+samuelcostae@users.noreply.github.com>
Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Naarcha-AWS <97990722+Naarcha-AWS@users.noreply.github.com>

_security/authentication-backends/openid-connect.md

@@ -336,6 +336,19 @@ opensearch.requestHeadersAllowlist: ["Authorization", "security_tenant"]
 To include OpenID Connect with other authentication types in the Dashboards sign-in window, see [Configuring sign-in options]({{site.url}}{{site.baseurl}}/security/configuration/multi-auth/).
 {: .note } 
 
+### Additional parameters
+
+Some identity providers require custom parameters to complete the authentication process. You can add custom parameters `opensearch_dashboards.yml` configuration file  under the `opensearch_security.openid.additional_parameters` namespace. You can find these additional parameters by making a GET request to your identity provider. This feature allows for greater flexibility and customization when communicating with various identity providers.
+
+In the following example, two custom parameters, `foo` and `acr_values`, and their values, `bar` and `1`, were found using a GET request to OpenID provider:
+
+```yml
+opensearch_security.openid.additional_parameters.foo: "bar"
+opensearch_security.openid.additional_parameters.acr_values: "1"
+```
+{% include copy.html %}
+
+
 
 #### Session management with additional cookies