Dubbo Admin Introductions

https://dubbo.apache.org/en/docs/v2.7/admin/ops/introduction
information is not current.
Default branch at https://github.com/apache/dubbo-admin.git is not a maven project, so
> git clone https://github.com/apache/dubbo-admin.git
> cd dubbo-admin
> mvn clean package
will give an error that project cannot be build.

Review the Dubbo Admin introductions page and the default branch of https://github.com/apache/dubbo-admin.git, starting by checking its current build files and documentation workflow. Update the page so its project checkout and build instructions match the repository, then verify that the documented command works or accurately reflects the current process.

Written by the indexing model from the issue text.