Add a -h/--help flag for the command line

[lumtis]

Help flag generally shows inline documentation for the command line. This is a good way to understand the usage without opening a browser

This issue is about adding the flag.

$create-cosmos-app -h

Usage: create-cosmos-app <project-directory> [options]

Options:
  -v, --version                            output the version number
  --name                                   name of the app
  --template <path-to-template>            specify a template for the created project
  ....