administration: fix incremental consistency check doc

The criterion is on indexation_timestamp, not creation date

bt5/erp5_administration/SkinTemplateItem/portal_skins/erp5_administration/Alarm_viewConsistencyCheckConfiguration/my_incremental_check.xml

@@ -173,7 +173,7 @@
                 </item>
                 <item>
                     <key> <string>title</string> </key>
-                    <value> <string>Only Check Documents Created since Last Run</string> </value>
+                    <value> <string>Only Check Documents Indexed since Last Run</string> </value>
                 </item>
               </dictionary>
             </value>