Show the Web UI main screenshot on EN/RU landing docs.

Keep a single main-console image with a Web UI guide link under it and
again at the page footer, without CI/Docker/License badges.

docs/README.md

@@ -5,6 +5,10 @@
 Guides for the VMware vSphere API simulator. Switch language with the header on each
 page. Russian mirrors live under [`ru/`](ru/README.md).
 
+![Web UI main console](images/web-ui-main.png)
+
+Interactive console walkthrough: [Web UI](web-ui.md).
+
 | Guide | Description |
 |---|---|
 | [Getting started](getting-started.md) | First successful lab session |
@@ -29,3 +33,5 @@ page. Russian mirrors live under [`ru/`](ru/README.md).
 
 Runnable cookbooks: [`examples/`](../examples/README.md).
 Integration suites: [`pulumi-tests/`](../pulumi-tests/README.md) (`make pulumi-tests`).
+
+Web UI console guide: [web-ui.md](web-ui.md).