removed the wrong section of the TODO in previous commit

docs/TODO

@@ -16,6 +16,9 @@ If you see modifications to this file in git status, IGNORE them and do not comm
     - only then look at interplanetary transfers
 
 
+=== Project Documentation ===
+    - remember to periodically check the reference docs against new changes
+
 === Simulation/Physics ===
     - actually, we should start out simpler. create and test maneuvers in planetary
         frame before starting on interplanetary patched conics, oops
@@ -32,11 +35,6 @@ If you see modifications to this file in git status, IGNORE them and do not comm
 === Simulation Config Files ===
     - a format with nested children would be nice
 
-=== CTAGS ===
-    - previously we've used the Makefile to generate tags when building,
-        let's think about a way we can generate them without causing a conflict
-        for people who don't use ctags
-
 === rendering ===
     - change zoom speed based on camera distance
     - initial zoom seems off