docs(customization): add "parents" to the list of fields in Changes

Author: unleashed

docs/customization.md

@@ -507,12 +507,16 @@ Each `Change` has the following fields:
 | scope | `str | None` | An optional scope |
 | message | `str` | The commit message body |
 | sha1 | `str` | The commit `sha1` |
+| parents | `list[str]` | The parent commit(s) `sha1`(s) |
 | author | `str` | The commit author name |
 | author_email | `str` | The commit author email |
 
 !!! Note
     The field values depend on the customization class and/or the settings you provide
 
+The `parents` field can be used to identify merge commits and generate a changelog based on those. Another use case
+is listing commits that belong to the same pull request.
+
 When using another template (either provided by a plugin or by yourself), you can also pass extra template variables
 by: