Fix schema column descriptions and clarify events requirements

Based on review feedback:
- Update HED column: 'HED Tag' → 'HED' display name, 'Tag' → 'tags' in description
- Fix stim_file path: /stimuli → /stimuli/ to prevent line breaks
- Add comma after 'sequence has started' for clarity
- Clarify events file requirements: 'at least one corresponding data file'
- Better explain inheritance principle for events files

Author: neuromechanist

src/modality-agnostic-files/events.md

@@ -20,10 +20,10 @@ duration).
    )
 }}
 
-Each `events.tsv` file REQUIRES a corresponding data file.
-It is also possible to have a single `events.tsv` file describing events
-for all participants and runs (see
-[Inheritance Principle](../common-principles.md#the-inheritance-principle)).
+Each `events.tsv` file REQUIRES at least one corresponding data file.
+Through the [Inheritance Principle](../common-principles.md#the-inheritance-principle),
+a single `events.tsv` file MAY describe events for multiple participants,
+sessions, and runs.
 As with all other tabular data, `events.tsv` files MAY be accompanied
 by a JSON file describing the columns in detail
 (see [Tabular Files](../common-principles.md#tabular-files)).
@@ -61,7 +61,7 @@ SHOULD be documented in an accompanying JSON sidecar file.
     if any acquired scans have been discarded before forming the imaging data file,
     ensure that an `onset` of 0 corresponds to the time the first image was stored.
     For example in case there is an in scanner training phase that
-    begins before the scanning sequence has started events from this sequence should
+    begins before the scanning sequence has started, events from this sequence should
     have negative onset time counting down to the beginning of the acquisition of
     the first volume.
 

src/schema/objects/columns.yaml

@@ -1,9 +1,9 @@
 ---
 HED:
   name: HED
-  display_name: HED Tag
+  display_name: HED
   description: |
-    Hierarchical Event Descriptor (HED) Tag.
+    Hierarchical Event Descriptor (HED) tags.
     See the [HED Appendix](SPEC_ROOT/appendices/hed.md) for details.
   type: string
 abbreviation:
@@ -582,7 +582,7 @@ stim_file:
     Represents the location of the stimulus file (such as an image, video, or
     audio file) presented at the given onset time.
     There are no restrictions on the file formats of the stimuli files,
-    but they should be stored in the `/stimuli` directory
+    but they should be stored in the `/stimuli/` directory
     (under the root directory of the dataset; with optional subdirectories).
     The values under the `stim_file` column correspond to a path relative to
     `/stimuli`.