Manual.rst: update sentence

Documentation/Manual.rst

@@ -290,7 +290,7 @@ Setup a *report* to manage all *forms*:
         }
     }
 
-If the QFQ installation becomes bigger and bigger, it me useful to know which form has been used how often, on which
+To keep the overview about all forms, it's useful to know which form has been used, how often, on which
 page and when. Find these information included in the `form-editor-usage`_ report.