- Bumps @version in mix.exs from 0.1.0 to 0.2.0.
- Assembles the 16 changelog.d fragments into the [0.2.0] section of
  CHANGELOG.md, grouped by heading, and deletes them in this commit
  per changelog.d/README.md.
- Moves the README and getting-started installation sections from the
  SHA-pinned git dependency to the exact Hex pin the same sections
  prescribed for this release ({:encryptor, "== 0.2.0"}).