Release v0.6.0

- FEATURE: interactive search mode when kubectx and kubens are ran without any
  arguments and fzf(1) is detected in PATH. (#71, #74)
- FIX: kubectx -d now doesn't ignore arguments after the first argument. (#75)
- FIX: empty output bug when TERM=vt100 even though NO_COLOR is set. (#57, #73)
- FIX: --help exits with code 0 now. (#69, #72)