add icon for uno.signature and uno.MergeDocuments

Change-Id: I1bc2bb232f9b1d7724b55a9e388150ea83af49f3
Reviewed-on: https://gerrit.libreoffice.org/35330Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Jan Holesovsky <kendy@collabora.com>

officecfg/registry/data/org/openoffice/Office/UI/GenericCommands.xcu

@@ -4500,6 +4500,9 @@
         <prop oor:name="TooltipLabel" oor:type="xs:string">
           <value xml:lang="en-US">Merge Track Changed Document</value>
         </prop>
+        <prop oor:name="Properties" oor:type="xs:int">
+          <value>1</value>
+        </prop>
       </node>
       <node oor:name=".uno:FlipHorizontal" oor:op="replace">
         <prop oor:name="Label" oor:type="xs:string">