message: updated readme for v2.2.1
diff: @@ -196,6 +196,8 @@ npm test
  ## Release Change Log
  +* 2.2.1
  + - Merged [PR#49](https://github.com/XeroAPI/xero-node/pull/49) - Merge PR#49 to change `createPayment` method to be `newPayment` in line with other entities, and introduce a new savePayments method for creating multiple payments in one call.
  * 2.2.0
  - Merged [PR#46](https://github.com/XeroAPI/xero-node/pull/46) - Merge PR#45 and provide library level support for boolean values (formerly this required string conversion).
  * 2.1.8
  