github: added PR template. (apache#539)

Author: moonming

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,17 @@
+NOTE: Please read the Contributing.md guidelines before submitting your patch:
+
+https://github.com/iresty/apisix/blob/master/Contributing.md#how-to-add-a-new-feature-or-change-an-existing-one
+
+### Summary
+
+SUMMARY_HERE
+
+### Full changelog
+
+* [Implement ...]
+* [Add related tests]
+* ...
+
+### Issues resolved
+
+Fix #XXX

README.md

@@ -41,7 +41,7 @@ For more detailed information, see the [White Paper](https://www.iresty.com/down
 - **[Limit-req](doc/plugins/limit-req.md)**
 - **[Limit-count](doc/plugins/limit-count.md)**
 - **[Limit-concurrency](doc/plugins/limit-conn.md)**
-- **OpenTracing: [Zipkin](doc/plugins/zipkin.md)**
+- **OpenTracing: [support Apache Skywalking and Zipkin](doc/plugins/zipkin.md)**
 - **Monitoring And Metrics**: [Prometheus](doc/plugins/prometheus.md)
 - **[gRPC transcoding](doc/plugins/grpc-transcoding.md)**：Supports protocol transcoding so that clients can access your gRPC API by using HTTP/JSON.
 - **[Serverless](doc/plugins/serverless.md)**: Invoke functions in each phase in APISIX.

README_CN.md

@@ -39,7 +39,7 @@ APISIX 通过插件机制，提供动态负载平衡、身份验证、限流限
 - **[限制速率](doc/plugins/limit-req-cn.md)**
 - **[限制请求数](doc/plugins/limit-count-cn.md)**
 - **[限制并发](doc/plugins/limit-conn-cn.md)**
-- **OpenTracing: [Zipkin](doc/plugins/zipkin.md)**
+- **OpenTracing: [支持 Apache Skywalking 和 Zipkin](doc/plugins/zipkin.md)**
 - **监控和指标**: [Prometheus](doc/plugins/prometheus-cn.md)
 - **[gRPC 协议转换](doc/plugins/grpc-transcoding-cn.md)**：支持协议的转换，这样客户端可以通过 HTTP/JSON 来访问你的 gRPC API。
 - **[Serverless](doc/plugins/serverless-cn.md)**: 在 APISIX 的每一个阶段，你都可以添加并调用自己编写的函数。