v0.2.0

The v0.2 mandatory crates release. See CHANGELOG.md for the full
breakdown.

Highlights:
- Four new shipped crates: rtb-redact, rtb-vcs (release-provider
  slice with 6 backends), rtb-update, rtb-docs.
- rtb-config gains Config::subscribe() + watch_files() (hot-reload
  feature).
- rtb-telemetry gains HttpSink + OtlpSink (remote-sinks feature)
  and auto-redacts Event.args / err_msg.
- Real CLI dispatch for the docs and update subcommands.
- Command::subcommand_passthrough default trait method;
  UpdaterBuilder::cache_dir override.