[FIX] clarify definition of events in common principles

Co-authored-by: VisLab <1189050+VisLab@users.noreply.github.com>

src/02-common-principles.md

@@ -48,9 +48,15 @@ misunderstanding we clarify them here.
     subject performed multiple conceptually different behaviors (with different
     sets of instructions) they will be considered one (combined) task.
 
-1.  **Event** - a stimulus or subject response recorded during a task. Each
-    event has an onset time and duration. Note that not all tasks will have
-    recorded events (e.g., “resting state”).
+1.  **Event** - something that happens or may be perceived as happening at a particular
+    moment during the recording.
+    Events are most commonly associated with sudden-onset sensory stimulus presentations
+    or with the distinct onset of a subject motor action.
+    Other events may include unplanned incidents,
+    changes in task instructions or experiment control parameters,
+    and noted data feature occurrences.
+    In BIDS, each event has an onset time and duration.
+    Note that not all tasks will have recorded events (e.g., "resting state").
 
 1.  **Run** - an uninterrupted repetition of data acquisition that has the same
     acquisition parameters and task (however events can change from run to run
@@ -99,8 +105,8 @@ A file name consists of a chain of *entities*, or key-value pairs, a *suffix* an
 Two prominent examples of entities are `subject` and `session`.
 
 For a data file that was collected in a given `session` from a given
-`subject`, the file name MUST begin with the string `sub-<label>_ses-<label>`. 
-If the `session` level is omitted in the folder structure, the file name MUST begin 
+`subject`, the file name MUST begin with the string `sub-<label>_ses-<label>`.
+If the `session` level is omitted in the folder structure, the file name MUST begin
 with the string `sub-<label>`, without `ses-<label>`.
 
 Note that `sub-<label>` corresponds to the `subject` entity because it has