text: Title: Documentation of properties required for row_result
  Body: **Describe the bug**
  
  The `row_result` object which is generated by each row import has undocumented properties.  This was raised [here](https://stackoverflow.com/a/68954762/39296).
  
  ** Solution **
  
  I guess attributes should be documented [here](https://django-import-export.readthedocs.io/en/latest/api_results.html#import_export.results.Result)
  
  **To Reproduce**
  
  **Versions (please complete the following information):**
   - Django Import Export: 2.5.0
   - Python (all)
   - Django (all
  
  
  