Update user docs for Central v2024.3

[matthew-white]

• Offline entities
  • If you use forms that create or update entities, you'll also need to update Collect (because the entity spec version will get bumped) - Migrate forms to use offline entities central#692
• View deleted Submissions and delete/undelete Submission #1873
• Changes to deployment instructions. Related to Prebuild Frontend central#656 and Use images for all services central#677
  • In the docs here, we suggest rebuilding nginx. But @lognaturel says that with v2024.2, nginx will just need to be restarted: "The logic to put the certs in the right place and everything is in the command that’s run at container start time."
  • @lognaturel: "In general I think we’ll have to edit docs to say build before v2024.2 [now v2024.3] and stop and restart in v2024.2 and after."
• Upgrade instructions