feat: warn the user on supplying unknown commands

[jamesgeorge007]

Fixes#493

node-lambda random

Unknown command random
Usage: node-lambda [options][command]
Options:
-V, --version output the version number
-h, --help output usage information
Commands:
deploy [options] Deploy your application to Amazon Lambda
package|zip [options] Create zipped package for Amazon Lambda deployment
run|execute [options] Run your Amazon Lambda application locally
setup [options] Sets up the .env file.

[DeviaVir]

👍 thanks for contributing