implementations: add a list of known implementations

Fixes #126

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

Makefile

@@ -30,7 +30,8 @@ DOC_FILES := \
 	layer.md \
 	config.md \
 	annotations.md \
-	considerations.md
+	considerations.md \
+	implementations.md
 
 FIGURE_FILES := \
 	img/media-types.png

implementations.md

@@ -0,0 +1,21 @@
+# OCI Image Implementations
+
+Projects or Companies currently adopting the OCI Image Specification
+
+* [projectatomic/skopeo](https://github.com/projectatomic/skopeo)
+* [Amazon Elastic Container Registry (ECR)](https://docs.aws.amazon.com/AmazonECR/latest/userguide/image-manifest-formats.html) ([announcement](https://aws.amazon.com/about-aws/whats-new/2017/01/amazon-ecr-supports-docker-image-manifest-v2-schema-2/))
+* [openSUSE/umoci](https://github.com/openSUSE/umoci)
+* [cloudfoundry/grootfs](https://github.com/cloudfoundry/grootfs) ([source](https://github.com/cloudfoundry/grootfs/blob/c3da26e1e463b51be1add289032f3dca6698b335/fetcher/remote/docker_src.go))
+* [Mesos plans](https://issues.apache.org/jira/browse/MESOS-5011) ([design doc](https://docs.google.com/document/d/1Pus7D-inIBoLSIPyu3rl_apxvUhtp3rp0_b0Ttr2Xww/edit#heading=h.hrvk2wboog4p))
+* [Docker](https://github.com/docker)
+ - [docker/containerd](https://github.com/docker/containerd)
+ - [docker/docker (`docker save/load` WIP)](https://github.com/docker/docker/pull/26369)
+ - [docker/distribution (registry PR)](https://github.com/docker/distribution/pull/2076)
+* [Containers](https://github.com/containers/)
+ - [containers/build](https://github.com/containers/build)
+ - [containers/image](https://github.com/containers/image)
+* [coreos/rkt](https://github.com/coreos/rkt)
+* [erikh/box](https://github.com/erikh/box)
+
+
+_(to add your project please open a [pull-request](https://github.com/opencontainers/image-spec/pulls))_