message: Update README.md
  links and add projects api support bullet
diff: ## Release of SDK with oAuth 2 support
  Version 4.x of Xero NodeJS SDK only supports oAuth2 authentication and the following API sets.
  -* accounting
  -* assets
  +* [accounting](https://developer.xero.com/documentation/api/api-overview)
  +* [assets](https://developer.xero.com/documentation/assets-api/overview)
  +* [projects](https://developer.xero.com/documentation/projects/overview-projects)
  ### Bank feeds support in OAuth 2
  An early release in a separate package is availalbe [bank feeds API](https://github.com/XeroAPI/xero-node-bankfeeds).
  