update main TODO

src/main.cpp

@@ -2,6 +2,7 @@
 /*
  * TODO:
  * - impulsive orbital maneuvers
+ * - replace instances of glm:: with using directives
  * - convert between satellite state vectors and orbital elements
  * - orbits with nu (true anom at T0) other than 0 degrees
  * - plane change maneuvers