add help csv-report link

app/partials/includes/modules/admin/project-csv.jade

@@ -15,7 +15,6 @@ section.project-csv(ng-controller='#{controller}  as ctrl', tg-select-input-text
            span.icon.icon-reload
            span Regenerate
 
-    a.help-button(href="", target="_blank")
+    a.help-button(href="https://taiga.io/support/csv-reports/", target="_blank")
         span.icon.icon-help
         span How to use this on my own spreadsheet?
-