Dubbo2.6 Demo

**Is your feature request related to a problem? Please describe.**

Currently, our project has some demo examples to verify the functionality of joylive-agent, including frameworks such as Spring Cloud, Dubbo3, and Dubbo2.7. However, there are still some demos that we have adapted but are missing, such as the Dubbo2.6 version.

目前我们项目里有一些demo示例用于验证joylive-agent的功能，包括spring cloud，dubbo3， dubbo2.7等框架。但是依然有一些我们做了适配，但是还缺少的demo示例。比如Dubbo2.6版本。

**Describe the solution you'd like**

We hope that volunteers can provide an example project for the joylive-agent project based on the Demo of Dubbo3 or Dubbo2.7 versions, for Dubbo2.6 version.

我们希望有志愿者能根据Dubbo3或者Dubbo2.7版本的Demo，为joylive-agent工程提供Dubbo2.6版本的示例工程。