runtime(doc): remove completed TODO

Completed in commit: c81dfaa69ceec9f6b88caf1dcdf2f859d4fcae47
(Patch 9.0.1621)

closes: #15763

Signed-off-by: Ben Scuron <bscuron19@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/todo.txt b/runtime/doc/todo.txt
index 3cfe59a..530b05d 100644
--- a/runtime/doc/todo.txt
+++ b/runtime/doc/todo.txt
@@ -1,4 +1,4 @@
-*todo.txt*      For Vim version 9.1.  Last change: 2024 Jul 11
+*todo.txt*      For Vim version 9.1.  Last change: 2024 Sep 29
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -38,9 +38,6 @@
 							*known-bugs*
 -------------------- Known bugs and current work -----------------------
 
-FILETYPE_FILE is defined to the same value in multiple places.
-Only use the one in feature.h.  Others too.
-
 Mapping with modifier is not recognized after a partial mapping.  Probably
 because the typeahead was simplified when looking for a matching mapping.
 Need to somehow undo the simplification.  #12002