katip-wai-0.1.2.1: CONTRIBUTING.md

# Contributing to katip-wai
I welcome all changes to `katip-wai`.

When making a PR make sure you have done the following:
  - Fixed all warnings and hlint suggestions
  - Added or modified tests if necessary 
  - Formatted with `fourmulu`
  - Added entries to the unreleased section at the top of [CHANGELOG.md](./CHANGELOG.md)
  - Ran [./scripts/test.sh](./scripts/test.sh) to ensure the project still builds with different compilers