Add linkerd plugin. Provided by dangdang.com

[hanahmily]

Linkerd is a transparent service mesh, designed to make modern applications safe and sane by transparently adding service discovery, load balancing, failure handling, instrumentation, and routing to all inter-service communication.

The plugin is designed to extract trace data from linkerd internal to the sky-walking collectors.

[wu-sheng]

Thanks for your contribution, we will wait for your pull request. The skywalking 3.3 will be a reserved version for you and dangdang, which includes linkerd plugin, and hopefully Sharding-JDBC as well.

[wu-sheng]

Closing this.