message: docs(cli): fix installation instructions
diff: ## Installation
  -This package is currently a work-in-progress and is set to `private`. Once it matures, it will be published externally to NPM.
  +Using NPM:
  +```
  +npm install @stylable/cli --save-dev
  +```
  +
  +Using Yarn:
  +```
  +yarn add @stylable/cli -D
  +```
  ## Usage
  