message: Add donation address to readme
diff: @@ -86,3 +86,5 @@ Special thanks to the following!
  - [jaimehgb/RaiBlocksWebAssemblyPoW](https://github.com/jaimehgb/RaiBlocksWebAssemblyPoW) - CPU PoW Implementation
  - [dcposch/blakejs](https://github.com/dcposch/blakejs) - Blake2b Implementation
  - [dchest/tweetnacl-js](https://github.com/dchest/tweetnacl-js) - Cryptography Implementation
  +
  +If you have found NanoVault useful and are feeling generous, you can donate at `xrb_318syypnqcgdouy3p3ekckwmnmmyk5z3dpyq48phzndrmmspyqdqjymoo8hj`
  