Add the example/sample to demo the Cross-LAN E2E Communication features?

**What would you like to be added/modified**:

- the example part: https://github.com/kubeedge/edgemesh#examples section only include [Cross-edge-cloud communication](https://edgemesh.netlify.app/guide/test-case.html#cross-edge-cloud) example for **cross-edge-cloud** example.
- Could you add the example to demo the **Cross-LAN E2E Communication** features? I am very interesting about this example.

**Why is this needed**:
Since I need this feature be demonstrated as a sample to use in our solution.

thanks very much.

Start with the repository's README Examples section and the linked Cross-edge-cloud communication guide to understand how the existing example is presented. Add a corresponding example for Cross-LAN E2E Communication, with enough usage information to demonstrate the feature as requested, and verify that it is linked from the examples section.

Written by the indexing model from the issue text.