- Split ledger history section into a parent concept page w/ online
deletion and history sharding as child pages
- Clarified how much data is stored in general
- Covered the special case for backfilling with advisory_delete enabled
(including updating the diagram)
- Changed full history recommendation to NuDB only
- Remove unused HTML tx queue diagram and associated images
- Add white (not transparent) background to some diagrams
- Fix line breaks on a couple images
- Change a couple other concept pages to use the new diagrams
- Remove some newly unused old diagrams
