actions 0.2.4

• fix post-release to make sure the sliding branch is created from the latest release tag. (#53, @kelly-sovacool)
• fix build-docker to set $DOCKERFILE_BASENAME for copying the Dockerfile inside the container. (#59, @kelly-sovacool)
• improvements to documentation website:
  • add contributors page. (#54, @kelly-sovacool)
  • list example workflows and improve navigation. (#55, @kelly-sovacool)
  • use FNL theme from ccbr_tools. (#57, @kelly-sovacool)
• New CLI and command ccbr_actions use-example to copy example GitHub Actions workflows to a repository. (#58, @kelly-sovacool)