Add information about manage_oidc privilege (#339)

Co-Authored-By: Lisa Cawley <[email protected]>

Author: jkakavas

docs/en/stack/security/authorization/privileges.asciidoc

@@ -52,6 +52,13 @@ roles of the user who created or updated them.
 
 --
 
+`manage_oidc`::
+Enables the use of {es} APIs
+({ref}/security-api-oidc-prepare-authentication.html[OpenID Connect Prepare Authentication],
+{ref}/security-api-oidc-authenticate.html[OpenID Connect Authenticate], and
+{ref}/security-api-oidc-logout.html[OpenID Connect Logout])
+to initiate and manage OpenID Connect authentication on behalf of other users.
+
 `manage_pipeline`::
 All operations on ingest pipelines.