add instructions to log into the registry

Author: bparees

admin_guide/docker_registry.adoc

@@ -112,6 +112,24 @@ staged for the given repository.
 <9> This file contains a reference to a specific layer that has been linked into
 this repository via an image.
 
+[[access]]
+== Accessing the Registry
+To access the registry directly such as to `docker push` or `docker pull` you must first login to the registry using an access token.  
+
+1.  Ensure you are logged in to OpenShift as a real user
+
+	$ oc login
+
+2.  Get your access token
+
+	$ oc whoami -t
+
+3. Log in to the docker registry
+
+	$ docker login -u <username> -e <any email address> -p <token value> <registry service host:port>
+
+You should now be able to perform docker pull/push operations.
+
 == Securing the Registry
 
 Optionally, you can secure the registry so that it serves traffic via TLS:
@@ -230,7 +248,7 @@ $ sudo systemctl restart docker
 ----
 ====
 +
-. Validate the docker client connection. Running `docker push` to the registry or `docker pull` from the registry should succeed:
+. Validate the docker client connection. Running `docker push` to the registry or `docker pull` from the registry should succeed.  Make sure you have link:#access[logged into the registry].
 +
 ====
 [options="nowrap"]
@@ -243,3 +261,5 @@ cf2616975b4a: Image successfully pushed
 Digest: sha256:3662dd821983bc4326bee12caec61367e7fb6f6a3ee547cbaff98f77403cab55
 ----
 ====
+
+