chore: capitalize all help commands

[notnmeyer]

Capitalizes the --help description in command output to match everything else.

before,

➜ task -- help
...
Available Commands:
...
  help          Help about any command

Flags:
  -h, --help            help for loops
  ...

after,

➜ task -- -h
...
Available Commands:
...
  help          Help about any command

Flags:
  -h, --help            Help for loops
...