Update doc-unversioned entries

* Sort them alphabetically
* Add missing stig

config.xml

@@ -296,12 +296,12 @@
   <doc cat="liberty" doc="quickstart" branches="SLL7">Registering RHEL 7 or CentOS Linux 7</doc>
 
   <!-- Unversioned -->
-  <doc cat="unvers" doc="pcidss/SLES-pci-dss" outputname="SLES-pci-dss" branches="main">Payment Card Industry Data Security Standard (PCI DSS) Guide</doc>
   <doc cat="unvers" doc="container-guide/Container-guide" outputname="SLES-container" branches="main">SUSE Linux Enterprise Containers</doc>
-  <doc cat="unvers" doc="suseconnect-visibility/SLE-suseconnect-visibility" outputname="SLE-suseconnect-visibility" branches="main">Enriched system visibility in the SUSE Customer Center</doc>
-  <doc cat="unvers" doc="trento/SLES-SAP-trento" outputname="SLES-SAP-trento" branches="main">Getting started with Trento Premium</doc>
-  <doc cat="unvers" doc="sap-ha-support/sap-ha-support" outputname="sap-ha-support" branches="main">Supported High Availability Solutions by SLES for SAP Applications</doc>
   <doc cat="unvers" doc="licenses/gfdl" outputname="licenses" branches="main">Licenses</doc>
-
+  <doc cat="unvers" doc="pcidss/SLES-pci-dss" outputname="SLES-pci-dss" branches="main">Payment Card Industry Data Security Standard (PCI DSS) Guide</doc>
+  <doc cat="unvers" doc="sap-ha-support/sap-ha-support" outputname="sap-ha-support" branches="main">Supported High Availability Solutions by SLES for SAP Applications</doc>
   <doc cat="submgt" doc="scc-hypervisor-collector/SLE-scc-hypervisor-collector" outputname="SLE-scc-hypervisor-collector" branches="main">Collecting hypervisor details in SUSE Customer Center</doc>
+  <doc cat="unvers" doc="stig/SLES-stig" outputname="SLES-stig" branches="main">Hardening SUSE Linux Enterprise with STIG</doc>
+  <doc cat="unvers" doc="suseconnect-visibility/SLE-suseconnect-visibility" outputname="SLE-suseconnect-visibility" branches="main">Enriched system visibility in the SUSE Customer Center</doc>
+  <doc cat="unvers" doc="trento/SLES-SAP-trento" outputname="SLES-SAP-trento" branches="main">Getting started with Trento Premium</doc>
 </indexconfig>