document_root/ is under k8s/

fixes `Forbidden path outside the build context` when building the
forthcoming `Dockerfile-nginx`

k8s/document_root/css/starter-template.css

@@ -0,0 +1,11 @@
+body {
+  padding-top: 50px;
+}
+.starter-template {
+  padding: 40px 15px;
+  text-align: left;
+}
+table.sslip {
+  border-spacing: 10px 2px;
+  border-collapse: separate;
+}