Add documentation on how to Bulk Edit & Batch Upload

[nicolas-cusan]

It would be great to be able to use this module https://github.com/colymba/GridFieldBulkEditingTools and define via config.yml on what models it should be used. As the ElementBase fields are defined on a project basis, bulk uploading might not always be relevant.

SlideshowElement:
  bulk_upload: true
  bulk_edit:
    - delete
  element_relations:
    Slides:
      - ImageElement