OSDOCS-15575 updated assembly

Author: wgabor0427

_topic_maps/_topic_map.yml

@@ -1239,6 +1239,8 @@ Topics:
     File: zero-trust-manager-install
   - Name: Deploying Zero Trust Workload Identity Manager operands
     File: zero-trust-manager-configuration
+  - Name: Zero Trust Workload Identity Manager upstream authority plugins
+    File: zero-trust-manager-upstream-authority
   - Name: Monitoring Zero Trust Workload Identity Manager
     File: zero-trust-manager-monitoring
   - Name: Uninstalling Zero Trust Workload Identity Manager

security/zero_trust_workload_identity_manager/zero-trust-manager-upstream-authority.adoc

@@ -0,0 +1,19 @@
+:_mod-docs-content-type: ASSEMBLY
+[id="zero-trust-manager-upstream-authority-plugins"]
+= Zero Trust Workload Identity Manager upstream authority plugins
+
+include::_attributes/common-attributes.adoc[]
+:context: zero-trust-manager-overview
+
+toc::[]
+
+:FeatureName: Zero Trust Workload Identity Manager
+include::snippets/technology-preview.adoc[]
+
+Upstream authority plugins are components that allow the SPIRE server to integrate with an existing Public Key Infrastructure (PKI) to obtain intermediate signing certificates. The SPIRE server then uses these intermediate certificates to cryptographically sign the {svid-full} that it issues to workloads. The plugins also allow the SPIRE server to use a pre-existing root of trust, rather than establishing a new, isolated one.
+
+The following upstream authority plugins are available:
+
+* cert-manager
+
+* vault