step-function-0.2.1: Changelog.md

# 0.2.1

- Support GHC-8.6.5...9.10.1

# 0.2

**Complete rewrite**.

- Uses 'Map' for the internal representation to be more effecient.
- Added discrete variants.
- GHC-8.4 support

# 0.1.1.2

- Build with GHC 8.2.2

# 0.1.1.1

Build with GHC 8.0.1.

# 0.1.1.0

StepFunction is now an instance of Functor.

# 0.1.0.2

Build with ghc 7.8.4.

# 0.1.0.1

Documentation fixes.

# 0.1.0.0

First import of package.