Exclude NOTEs as refile targets

NOTEs are meant to hold information for the project at hand, and not to collect
tasks, because NOTEs are meant to live longer than those tasks.  Use dedicated
subprojects to group tasks.  Task may (and probably should) refer to NOTEs for
keeping long lasting information, though.

site-lisp/db-org.el

@@ -297,7 +297,9 @@ tag PERIODIC."
   (and
    ;; Exclude DONE state tasks from refile targets (from bh)
    (not (member (nth 2 (org-heading-components))
-                org-done-keywords))))
+                org-done-keywords))
+   ;; Do not refile to NOTEs, as those are meant to keep information, not tasks
+   (not (member "NOTE" (org-get-tags)))))
 
 
 ;;; Reset checklists