Start to write protocol section.

docs/en/protocols/README.md

 # Protocols
+There are two types of protocols list here. 
 
-* [Cross Process Propagation Headers Protocol, v1.0](Skywalking-Cross-Process-Propagation-Headers-Protocol-v1.md)
-* [SkyWalking Trace Data Protocol](Trace-Data-Protocol.md)
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+- **Probe Protocol**. Include the descriptions and defines about how agent send collected metric data and traces, also the formats of each entities.
+
+- **Query Protocol**. The backend provide query capability to SkyWalking own UI and others. These queries are based on GraphQL.
+
+## Probe Protocol
+They also related to the probe group, for understand that, look [Concepts and Designs](../concepts-and-designs/README.md) document.
+These groups are **Language based native agent protocol**, **Service Mesh protocol** and **3rd-party instrument protocol**.  
+
+
+## Language based native agent protocol
+This protocol is combined from two parts:
+* [Cross Process Propagation Headers Protocol](Skywalking-Cross-Process-Propagation-Headers-Protocol-v1.md) is for in-wire propagation.
+which is usually used to carrier the necessary info to build trace.
+* [SkyWalking Trace Data Protocol](Trace-Data-Protocol.md) define the communication way and format between agent and backend.
+
+
+## Service Mesh probe protocol
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