add comments as to why we need to check that the player is grounded or not; only run once during initial cell loading

apps/openmw/mwworld/scene.cpp

@@ -447,7 +447,9 @@ namespace MWWorld
                     mPhysics->disableWater();
 
                 const auto player = MWBase::Environment::get().getWorld()->getPlayerPtr();
-                if (player.getCell() == cell) {
+
+                // By default the player is grounded, with the scene fully loaded, we validate and correct this.
+                if (player.getCell() == cell) { // Only run once, during initial cell load.
                     mPhysics->traceDown(player, player.getRefData().getPosition().asVec3(), 10.f);
                 }