fix: documents docs compare

fix: avoid tempering last_updated for individual symbol when file is …

…updated

feat: deletion case handling (#16)

* fix: build on stable

* refactor: handle symbol deletion case

* feat: walk & validate file persistence

* chore(ci): build on stable

* cleanup: immediate deref

chore: update readme

chore(chumbucket) - cleanup & tokio update

chore(ver) - bump chumbucket

feat(cb) - preserve index content if no partial diff

feat(cb) - build index subcommand

chore(ver) - bump cb

feat(chumbucket) - walker from & bundle version