Add Default Task To List All Tasks

One thing I like about just is that if you run just by itself, the default behavior is to list out all the commands it can run.

Taskfile technically does this as well, but with a warning at the end:

❯ task
task: Available tasks for this project:
* notes:              Interactive picker for notes tasks
* notes:diff:         Show uncommitted changes in notes
* notes:edit:         All-in-one edit, commit, and push notes
* notes:log:          Show recent commit history for notes
* notes:open:         Opens NOTES.md (syncs latest changes first) in default editor
* notes:push:         Commit and push changes to notes submodule
* notes:status:       Check status of notes submodule
* notes:sync:         Sync latest changes from the notes submodule
task: Task "default" does not exist

I prefer to tidy this up a little by adding task --list as the default in my Taskfile.yml.

  default:
    desc: Show available commands
    cmds:
      - task --list

Now when I run task with no arguments, I get this minutely nicer version:

❯ task
Alias tip: t
task: [default] task --list
task: Available tasks for this project:
* default:            Show available commands
* notes:              Interactive picker for notes tasks
* notes:diff:         Show uncommitted changes in notes
* notes:edit:         All-in-one edit, commit, and push notes
* notes:log:          Show recent commit history for notes
* notes:open:         Opens NOTES.md (syncs latest changes first) in default editor
* notes:push:         Commit and push changes to notes submodule
* notes:status:       Check status of notes submodule
* notes:sync:         Sync latest changes from the notes submodule

Notice there is no task: Task "default" does not exist warning at the end.