improve comment

Author: drammock

mne_bids/read.py

@@ -531,7 +531,8 @@ def _handle_events_reading(events_fname, raw):
     logger.info(f"Reading events from {events_fname}.")
     events_dict = _from_tsv(events_fname)
 
-    # drop events where onset is n/a
+    # drop events where onset is n/a; we can't annotate them and thus don't need entries
+    # for them in event_id either
     events_dict = _drop(events_dict, "n/a", "onset")
 
     # Get event descriptions. Use `trial_type` column if available.