Change cli help texts to reflect mandatory and non-mandatory flags

## Description

Ensure that all `ecctl` commands comply with the style syntax, Flags / arguments need to be clearly demarcated as mandatory and/or optional. See Google's style guide

## Old description
Mandatory flags should not appear in [] as IEEE Standards suggest

Example: `ecctl deployment elasticsearch create [--file] [--capacity|--version|--zones] [name] [flags]`

Capacity, version, zones are all mandatory.