Bulk update 7 4

[ekansa]

brief description of changes

Start of guidance for use of the Bulk Data Manager. So far, this only covers how to activate the Bulk Data Manager. I need to get Celery to work before documenting how to use this feature.

issues addressed

7.4 release notes

further comments

see test deployment: https://arches.readthedocs.io/en/bulk_update_7_4/administering/bulk-data-manager/

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This box must be checked

• [X ] the PR branch was originally made from the base branch

This box should be checked

• [X] after these changes the docs build locally without error

This box should only be checked you intend to follow through on it (we can do it on our end too)

• [ ] I will cherry-pick all commits in this PR into other branches that should have them after this PR is merged