Fixed mistaken tool name.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@16331 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/CMFActivity/dtml/explainActivityTool.dtml

 <dtml-var manage_page_header>
 <dtml-var manage_tabs>
 
-<p>Explain CategoryTool</p>
+<p>Explain ActivityTool</p>
 
 <dtml-var manage_page_footer>