message: Changelog.md updates
diff: ### 0.2.0 (unreleased)
  +- Fixes SGR decorations to use designated underline thickness and underline position.
  - Adds VT sequence for enabling/disabling debug logging. `CSI ? 46 h` and `CSI ? 46 l` and CLI option `-d`.
  +- Adds improved debug logging.
  - ...
  ### 0.1.1 (2020-12-31)
  