doc improvement

Documentation.html

@@ -3489,7 +3489,7 @@ To create a new, empty mimetype please see libraries/transformations/template_ge
     <li>Select the name of the new page (the action choice being set to Edit)
         and click Go.</li>
     <li>Select a table from the list, enter its coordinates and click Go.<br />
-        Coordinates are expressed in millimeters; your diagram will
+        Coordinates are relative; your diagram will
         be automatically scaled to fit the page. When initially placing tables
         on the page, just pick any coordinates -- say, 50x50. After clicking
         Go, you can then use the <a href="#wysiwyg">graphical editor</a> to