Synchronize push reference with man page

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit dddea689ab45ce146e6ac3a1199235e1f36ffe29)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

docs/reference/commandline/push.md

@@ -22,9 +22,42 @@ Options:
 
 Use `docker push` to share your images to the [Docker Hub](https://hub.docker.com)
 registry or to a self-hosted one.
-[Read more about valid image names and tags](tag.md).
+
+Refer to the [`docker tag`](tag.md) reference for more information about valid
+image and tag names.
 
 Killing the `docker push` process, for example by pressing `CTRL-c` while it is
-running in a terminal, will terminate the push operation.
+running in a terminal, terminates the push operation.
 
 Registry credentials are managed by [docker login](login.md).
+
+## EXAMPLES
+
+### Pushing a new image to a registry
+
+First save the new image by finding the container ID (using [`docker ps`](ps.md))
+and then committing it to a new image name.  Note that only `a-z0-9-_.` are
+allowed when naming images:
+
+```bash
+$ docker commit c16378f943fe rhel-httpd
+```
+
+Now, push the image to the registry using the image ID. In this example the
+registry is on host named `registry-host` and listening on port `5000`. To do
+this, tag the image with the host name or IP address, and the port of the
+registry:
+
+```bash
+$ docker tag rhel-httpd registry-host:5000/myadmin/rhel-httpd
+$ docker push registry-host:5000/myadmin/rhel-httpd
+```
+
+Check that this worked by running:
+
+```bash
+$ docker images
+```
+
+You should see both `rhel-httpd` and `registry-host:5000/myadmin/rhel-httpd`
+listed.