Add Open Collective badge and button

README.md

@@ -4,6 +4,7 @@
 [![Coverage Status](https://img.shields.io/codecov/c/github/kr1sp1n/node-vault/master.svg?style=flat-square)](https://codecov.io/gh/kr1sp1n/node-vault/branch/master)
 [![Download Status](https://img.shields.io/npm/dm/node-vault.svg?style=flat-square)](https://www.npmjs.com/package/node-vault)
 [![Dependency Status](https://img.shields.io/david/kr1sp1n/node-vault.svg?style=flat-square)](https://david-dm.org/kr1sp1n/node-vault)
+[![Open Collective backers and sponsors](https://img.shields.io/opencollective/all/node-vault?style=flat-square)](https://opencollective.com/node-vault/contribute)
 
 A client for the HTTP API of HashiCorp's [Vault] written for Node.js.
 
@@ -92,7 +93,7 @@ Now you are able to run all of the other [examples]:
 node example/policies.js
 ```
 
-
+[![Backers](https://opencollective.com/node-vault/tiers/backers.svg?avatarHeight=80&width=600)](https://opencollective.com/node-vault/contribute)
 
 [examples]: https://github.com/kr1sp1n/node-vault/tree/master/example
 [docker-compose.yml]: https://github.com/kr1sp1n/node-vault/tree/master/docker-compose.yml