chore(readme): remove Greenkeeper badge (#10)

Co-authored-by: greenkeeper[bot] <23040076+greenkeeper[bot]@users.noreply.github.com>

Author: greenkeeper[bot]

README.md

@@ -15,7 +15,7 @@ governing permissions and limitations under the License.
 [![Build Status](https://travis-ci.com/adobe/aio-lib-core-errors.svg?branch=master)](https://travis-ci.com/adobe/aio-lib-core-errors)
 [![License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](https://opensource.org/licenses/Apache-2.0) 
 [![Codecov Coverage](https://img.shields.io/codecov/c/github/adobe/aio-lib-core-errors/master.svg?style=flat-square)](https://codecov.io/gh/adobe/aio-lib-core-errors/)
-[![Greenkeeper badge](https://badges.greenkeeper.io/adobe/aio-lib-core-errors.svg)](https://greenkeeper.io/)
+
 
 This contains the base class for all Adobe I/O Core Errors. Use this as an Error class subclass for all your SDK Errors.