Add docs on how to configure certs

configure/use-your-certificates.md

@@ -0,0 +1,51 @@
++++
+title = "Use your own certificates"
+description = "Learn how to configure Docker Trusted Registry to use your own certificates"
+keywords = ["Universal Control Plane, UCP, certificate, authentiation, tls"]
+[menu.main]
+parent="workw_dtr_configure"
+identifier="dtr-configure-certs"
+weight=0
++++
+
+# Use your own certificates
+
+By default the DTR services are exposed using HTTPS, to ensure all
+communications between clients and DTR is encrypted. Since DTR
+replicas use self-signed certificates for this, when a client accesses
+DTR, their browsers won't trust this certificate, so the browser displays a
+warning message.
+
+You can configure DTR to use your own certificates, so that it is automatically
+trusted by your users' browser and client tools.
+
+## Replace the server certificates
+
+To configure DTR to use your own certificates and keys, go to the
+**DTR web UI**, navigate to the **Settings** page, and scroll down to the
+**Domain** section.
+
+![](../images/use-your-certificates-1.png)
+
+
+Set the DTR domain name and upload the certificates and key:
+
+* Load balancer/public address, is the domain name clients will use to access DTR.
+* TLS certificate, is the server certificate and any intermediate CA public
+certificates. This certificate needs to be valid for the DTR public address,
+and have SANs for all addresses used to reach the DTR replicas, including load
+balancers.
+* TLS private key is the server private key.
+* TLS CA is the root CA public certificate.
+
+Finally, click **Save** for the changes to take effect.
+
+If you're using certificates issued by a globally trusted certificate authority,
+any web browser or client tool should now trust DTR. If you're using an internal
+certificate authority, you'll need to [configure your system to trust that
+certificate authority](../repos-and-images/index.md).
+
+## Where to go next
+
+* [Configure your Docker Engine](../repos-and-images/index.md)
+* [Pull an image](../repos-and-images/pull-an-image.md)