Put the note about generic implementations at the end of the section

doc/doxygen/chapters/06tasks.doxy

@@ -213,9 +213,6 @@ struct starpu_codelet cl = {
 };
 \endcode
 
-Note: the most generic variant should be provided first, as some schedulers are
-not able to try the different variants.
-
 Another example is having specialized implementations for some given common
 sizes, for instance here we have a specialized implementation for 1024x1024
 matrices:
@@ -251,6 +248,9 @@ struct starpu_codelet cl = {
 };
 \endcode
 
+Note: the most generic variant should be provided first, as some schedulers are
+not able to try the different variants.
+
 \section InsertTaskUtility Insert Task Utility
 
 StarPU provides the wrapper function starpu_task_insert() to ease