Bugfix, feature and docs minor update:

• add non-interactive create/enter using env variables
• docs: add license headers and switch license to markdown format
• docs: fix backup/restore commands
• add custom --home flag for distrobox-create to use custom HOMEs for containers
• fix custom mounts routine moving it from create to init
• add new distrobox wrapper to use the commands without the hyphens (eg: distrobox create or distrobox enter)
• add new quality of life commands:
  • distrobox-list: list created pet containers, green if running, yellow if stopped
  • distrobox-rm: remove a created pet container