Docs: Fix inaccuracies in Holdings Import Profiles sections

Docs: Fix inaccuracies in Holdings Import Profiles sections

In dev/_importing_materials_in_the_staff_client.html:

- Fix "For more details" link
- Remove remaining references to "Keep" (some were removed previously in
  commit 7570423802)
- Remove "static values" references from both pages (not supported)
- Add link to related Library Settings

In dev/_import_item_attributes_2.html:

- Remove sentence fragment left behind when previous "Keep" reference
  was deleted.
- Add table row for "Parts Data"

Signed-off-by: Remington Steed <rjs7@calvin.edu>