Switch ImageLayers badges to MicroBadger badges

ImageLayers seems not support Docker Registry v2 API.

See [1], [2], [3], [4], [5] for details.

[1]: https://medium.com/microscaling-systems/be-docker-image-conscious-deef8008fdce
[2]: CenturyLinkLabs/docker-reg-client#5
[3]: microscaling/imagelayers-graph#94
[4]: microscaling/imagelayers-graph#96
[5]: microscaling/imagelayers-graph#92

README.md

@@ -3,7 +3,8 @@ Docker confd
 
 [![Docker Stars](https://img.shields.io/docker/stars/dochang/confd.svg)](https://hub.docker.com/r/dochang/confd/)
 [![Docker Pulls](https://img.shields.io/docker/pulls/dochang/confd.svg)](https://hub.docker.com/r/dochang/confd/)
-[![](https://badge.imagelayers.io/dochang/confd:latest.svg)](https://imagelayers.io/?images=dochang/confd:latest 'Get your own badge on imagelayers.io')
+[![](https://images.microbadger.com/badges/image/dochang/confd:latest.svg)](http://microbadger.com/images/dochang/confd:latest "Get your own image badge on microbadger.com")
+[![](https://images.microbadger.com/badges/version/dochang/confd:latest.svg)](http://microbadger.com/images/dochang/confd:latest "Get your own version badge on microbadger.com")
 
 A Docker image of [confd][].