Add release notes for version 8.1.2

Added release notes for version 8.1.2 with updates and issues.

Author: danirabbit

data/greeter.metainfo.xml.in

@@ -37,6 +37,18 @@
   <update_contact>contact_at_elementary.io</update_contact>
 
   <releases>
+    <release version="8.1.2" date="2026-01-05" urgency="medium">
+      <description>
+        <p>Minor updates:</p>
+        <ul>
+          <li>Updated translations</li>
+        </ul>
+      </description>
+      <issues>
+        <issue url="https://github.com/elementary/installer/issues/917">Installer window blocks GParted window</issue>
+      </issues>
+    </release>
+
     <release version="8.1.1" date="2025-11-25" urgency="medium">
       <description>
         <p>Minor updates:</p>